diff --git a/src/main/org/apache/tools/ant/taskdefs/Echo.java b/src/main/org/apache/tools/ant/taskdefs/Echo.java
index f6be4808d..02bd1f0d3 100644
--- a/src/main/org/apache/tools/ant/taskdefs/Echo.java
+++ b/src/main/org/apache/tools/ant/taskdefs/Echo.java
@@ -67,6 +67,8 @@ import java.io.IOException;
  *
  * @author costin@dnt.ro
  *
+ * @since Ant 1.1
+ *
  * @ant.task category="utility"
  */
 public class Echo extends Task {
diff --git a/src/main/org/apache/tools/ant/taskdefs/Jar.java b/src/main/org/apache/tools/ant/taskdefs/Jar.java
index e964e172e..946d920fc 100644
--- a/src/main/org/apache/tools/ant/taskdefs/Jar.java
+++ b/src/main/org/apache/tools/ant/taskdefs/Jar.java
@@ -59,6 +59,7 @@ import org.apache.tools.ant.FileScanner;
 import org.apache.tools.ant.Project;
 import org.apache.tools.ant.types.ZipFileSet;
 import org.apache.tools.ant.types.EnumeratedAttribute;
+import org.apache.tools.ant.util.StringUtils;
 import org.apache.tools.zip.ZipOutputStream;
 
 import java.io.IOException;
@@ -80,6 +81,8 @@ import java.util.Enumeration;
  * @author James Davidson <a href="mailto:duncan@x180.com">duncan@x180.com</a>
  * @author Brian Deitte <a href="mailto:bdeitte@macromedia.com">bdeitte@macromedia.com</a>
  *
+ * @since 1.1
+ *
  * @ant.task category="packaging"
  */
 public class Jar extends Zip {
@@ -88,6 +91,8 @@ public class Jar extends Zip {
 
     /** merged manifests added through addConfiguredManifest */
     private Manifest configuredManifest;
+    /** shadow of the above if upToDate check alters the value */
+    private Manifest savedConfiguredManifest;
 
     /**  merged manifests added through filesets */
     private Manifest filesetManifest;
@@ -108,9 +113,10 @@ public class Jar extends Zip {
     private Manifest manifest;
 
     /**
-     * The file found from the 'manifest' attribute.  This can be either the location of a manifest,
-     * or the name of a jar added through a fileset.  If its the name of an added jar, the manifest is
-     * looked for in META-INF/MANIFEST.MF
+     * The file found from the 'manifest' attribute.  This can be
+     * either the location of a manifest, or the name of a jar added
+     * through a fileset.  If its the name of an added jar, the
+     * manifest is looked for in META-INF/MANIFEST.MF
      */
     private File manifestFile;
 
@@ -145,19 +151,20 @@ public class Jar extends Zip {
         index = flag;
     }
 
-    public void addConfiguredManifest(Manifest newManifest) throws ManifestException {
+    public void addConfiguredManifest(Manifest newManifest) 
+        throws ManifestException {
         if (configuredManifest == null) {
             configuredManifest = newManifest;
-        }
-        else {
+        } else {
             configuredManifest.merge(newManifest);
         }
+        savedConfiguredManifest = configuredManifest;
     }
 
     public void setManifest(File manifestFile) {
         if (!manifestFile.exists()) {
-            throw new BuildException("Manifest file: " + manifestFile + " does not exist.",
-                                     getLocation());
+            throw new BuildException("Manifest file: " + manifestFile +
+                                     " does not exist.", getLocation());
         }
 
         this.manifestFile = manifestFile;
@@ -172,9 +179,10 @@ public class Jar extends Zip {
             newManifest = getManifest(r);
         }
         catch (IOException e) {
-            throw new BuildException("Unable to read manifest file: " + manifestFile, e);
-        }
-        finally {
+            throw new BuildException("Unable to read manifest file: " 
+                                     + manifestFile 
+                                     + " (" + e.getMessage() + ")", e);
+        } finally {
             if (r != null) {
                 try {
                     r.close();
@@ -195,10 +203,12 @@ public class Jar extends Zip {
         }
         catch (ManifestException e) {
             log("Manifest is invalid: " + e.getMessage(), Project.MSG_ERR);
-            throw new BuildException("Invalid Manifest: " + manifestFile, e, getLocation());
+            throw new BuildException("Invalid Manifest: " + manifestFile, 
+                                     e, getLocation());
         }
         catch (IOException e) {
-            throw new BuildException("Unable to read manifest file", e);
+            throw new BuildException("Unable to read manifest file"
+                                     + " (" + e.getMessage() + ")", e);
         }
         return newManifest;
     }
@@ -219,13 +229,14 @@ public class Jar extends Zip {
         throws IOException, BuildException
     {
         String ls = System.getProperty("line.separator");
+
         try {
             Manifest finalManifest = Manifest.getDefaultManifest();
 
             if (manifest == null) {
                 if (manifestFile != null) {
-                    // if we haven't got the manifest yet, attempt to get it now and
-                    // have manifest be the final merge
+                    // if we haven't got the manifest yet, attempt to
+                    // get it now and have manifest be the final merge
                     manifest = getManifest(manifestFile);
                     finalManifest.merge(filesetManifest);
                     finalManifest.merge(configuredManifest);
@@ -234,7 +245,8 @@ public class Jar extends Zip {
                 else if (configuredManifest != null) {
                     // configuredManifest is the final merge
                     finalManifest.merge(filesetManifest);
-                    finalManifest.merge(configuredManifest, ! mergeManifestsMain);
+                    finalManifest.merge(configuredManifest, 
+                                        ! mergeManifestsMain);
                 }
                 else if (filesetManifest != null) {
                     // filesetManifest is the final (and only) merge
@@ -247,11 +259,14 @@ public class Jar extends Zip {
                 finalManifest.merge(manifest, ! mergeManifestsMain);
             }
 
-            for (Enumeration e = finalManifest.getWarnings(); e.hasMoreElements(); ) {
-                log("Manifest warning: " + (String)e.nextElement(), Project.MSG_WARN);
+            for (Enumeration e = finalManifest.getWarnings(); 
+                 e.hasMoreElements(); ) {
+                log("Manifest warning: " + (String)e.nextElement(), 
+                    Project.MSG_WARN);
             }
 
-            // need to set the line.separator as \r\n due to a bug with the jar verifier
+            // need to set the line.separator as \r\n due to a bug
+            // with the jar verifier
             System.getProperties().put("line.separator", "\r\n");
 
             zipDir(null, zOut, "META-INF/");
@@ -261,8 +276,10 @@ public class Jar extends Zip {
             finalManifest.write(writer);
             writer.flush();
 
-            ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
-            super.zipFile(bais, zOut, "META-INF/MANIFEST.MF", System.currentTimeMillis(), null);
+            ByteArrayInputStream bais = 
+                new ByteArrayInputStream(baos.toByteArray());
+            super.zipFile(bais, zOut, "META-INF/MANIFEST.MF", 
+                          System.currentTimeMillis(), null);
             super.initZipOutputStream(zOut);
         }
         catch (ManifestException e) {
@@ -294,7 +311,8 @@ public class Jar extends Zip {
     private void createIndexList(ZipOutputStream zOut) throws IOException {
         ByteArrayOutputStream baos = new ByteArrayOutputStream();
         // encoding must be UTF8 as specified in the specs.
-        PrintWriter writer = new PrintWriter(new OutputStreamWriter(baos, "UTF8"));
+        PrintWriter writer = new PrintWriter(new OutputStreamWriter(baos, 
+                                                                    "UTF8"));
 
         // version-info blankline
         writer.println("JarIndex-Version: 1.0");
@@ -329,7 +347,8 @@ public class Jar extends Zip {
         }
 
         writer.flush();
-        ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
+        ByteArrayInputStream bais = 
+            new ByteArrayInputStream(baos.toByteArray());
         super.zipFile(bais, zOut, INDEX_NAME, System.currentTimeMillis(), null);
     }
 
@@ -349,7 +368,8 @@ public class Jar extends Zip {
     /**
      * Overriden from Zip class to deal with manifests
      */
-    protected void zipFile(InputStream is, ZipOutputStream zOut, String vPath, long lastModified, File file)
+    protected void zipFile(InputStream is, ZipOutputStream zOut, String vPath,
+                           long lastModified, File file)
         throws IOException
     {
         if ("META-INF/MANIFEST.MF".equalsIgnoreCase(vPath))  {
@@ -361,7 +381,8 @@ public class Jar extends Zip {
 
     private void filesetManifest(File file, InputStream is) {
         if (manifestFile != null && manifestFile.equals(file)) {
-            // If this is the same name specified in 'manifest', this is the manifest to use
+            // If this is the same name specified in 'manifest', this
+            // is the manifest to use
             log("Found manifest " + file, Project.MSG_VERBOSE);
             if (is != null) {
                 manifest = getManifest(new InputStreamReader(is));
@@ -372,7 +393,8 @@ public class Jar extends Zip {
         }
         else if (mergeManifests) {
             // we add this to our group of fileset manifests
-            log("Found manifest to merge in file " + file, Project.MSG_VERBOSE);
+            log("Found manifest to merge in file " + file, 
+                Project.MSG_VERBOSE);
 
             try
             {
@@ -390,8 +412,10 @@ public class Jar extends Zip {
         }
         else {
             // assuming 'skip' otherwise
-            log("File " + file + " includes a META-INF/MANIFEST.MF which will be ignored. " +
-                "To include this file, set filesetManifest to a value other than 'skip'.", Project.MSG_WARN);
+            log("File " + file 
+                + " includes a META-INF/MANIFEST.MF which will be ignored. " 
+                + "To include this file, set filesetManifest to a value other "
+                + "than 'skip'.", Project.MSG_WARN);
         }
     }
 
@@ -399,27 +423,33 @@ public class Jar extends Zip {
      * Check whether the archive is up-to-date;
      * @param scanners list of prepared scanners containing files to archive
      * @param zipFile intended archive file (may or may not exist)
-     * @return true if nothing need be done (may have done something already); false if
-     *         archive creation should proceed
+     * @return true if nothing need be done (may have done something
+     *         already); false if archive creation should proceed
      * @exception BuildException if it likes
      */
-    protected boolean isUpToDate(FileScanner[] scanners, File zipFile) throws BuildException {
+    protected boolean isUpToDate(FileScanner[] scanners, File zipFile) 
+        throws BuildException {
         // need to handle manifest as a special check
         if (configuredManifest != null || manifestFile == null) {
             java.util.zip.ZipFile theZipFile = null;
             try {
                 theZipFile = new java.util.zip.ZipFile(zipFile);
-                java.util.zip.ZipEntry entry = theZipFile.getEntry("META-INF/MANIFEST.MF");
+                java.util.zip.ZipEntry entry = 
+                    theZipFile.getEntry("META-INF/MANIFEST.MF");
                 if (entry == null) {
-                    log("Updating jar since the current jar has no manifest", Project.MSG_VERBOSE);
+                    log("Updating jar since the current jar has no manifest", 
+                        Project.MSG_VERBOSE);
                     return false;
                 }
-                Manifest currentManifest = new Manifest(new InputStreamReader(theZipFile.getInputStream(entry)));
+                Manifest currentManifest = 
+                    new Manifest(new InputStreamReader(theZipFile
+                                                       .getInputStream(entry)));
                 if (configuredManifest == null) {
-                     configuredManifest = Manifest.getDefaultManifest();
+                    configuredManifest = Manifest.getDefaultManifest();
                 }
                 if (!currentManifest.equals(configuredManifest)) {
-                    log("Updating jar since jar manifest has changed", Project.MSG_VERBOSE);
+                    log("Updating jar since jar manifest has changed", 
+                        Project.MSG_VERBOSE);
                     return false;
                 }
             }
@@ -462,6 +492,8 @@ public class Jar extends Zip {
         super.cleanUp();
 
         manifest = null;
+        configuredManifest = savedConfiguredManifest;
+        filesetManifest = null;
     }
 
     /**
@@ -474,7 +506,6 @@ public class Jar extends Zip {
     public void reset() {
         super.reset();
         configuredManifest = null;
-        filesetManifest = null;
         mergeManifests = false;
         mergeManifestsMain = false;
         manifestFile = null;
diff --git a/src/main/org/apache/tools/ant/taskdefs/Zip.java b/src/main/org/apache/tools/ant/taskdefs/Zip.java
index 96b38ed66..3b4770c15 100644
--- a/src/main/org/apache/tools/ant/taskdefs/Zip.java
+++ b/src/main/org/apache/tools/ant/taskdefs/Zip.java
@@ -61,6 +61,7 @@ import java.io.FileInputStream;
 import java.io.OutputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.ByteArrayInputStream;
+import java.util.Enumeration;
 import java.util.Hashtable;
 import java.util.Stack;
 import java.util.Vector;
@@ -73,6 +74,7 @@ import org.apache.tools.ant.Project;
 import org.apache.tools.ant.DirectoryScanner;
 import org.apache.tools.ant.types.FileSet;
 import org.apache.tools.ant.types.EnumeratedAttribute;
+import org.apache.tools.ant.types.PatternSet;
 import org.apache.tools.ant.types.ZipFileSet;
 import org.apache.tools.ant.types.ZipScanner;
 import org.apache.tools.ant.util.FileUtils;
@@ -88,6 +90,8 @@ import org.apache.tools.zip.ZipEntry;
  * @author Jon S. Stevens <a href="mailto:jon@clearink.com">jon@clearink.com</a>
  * @author <a href="mailto:stefan.bodewig@epost.de">Stefan Bodewig</a>
  *
+ * @since Ant 1.1
+ *
  * @ant.task category="packaging"
  */
 public class Zip extends MatchingTask {
@@ -96,9 +100,12 @@ public class Zip extends MatchingTask {
     private File baseDir;
     protected Hashtable entries = new Hashtable();
     private Vector groupfilesets = new Vector();
+    private Vector filesetsFromGroupfilesets = new Vector();
     protected String duplicate = "add";
     private boolean doCompress = true;
     private boolean doUpdate = false;
+    // shadow of the above if the value is altered in execute
+    private boolean savedDoUpdate = false;
     private boolean doFilesonly = false;
     protected String archiveType = "zip";
 
@@ -109,9 +116,11 @@ public class Zip extends MatchingTask {
     protected Hashtable addedDirs = new Hashtable();
     private Vector addedFiles = new Vector();
 
-    /** true when we are adding new files into the Zip file, as opposed to
-        adding back the unchanged files */
-    private boolean addingNewFiles;
+    /** 
+     * true when we are adding new files into the Zip file, as opposed
+     * to adding back the unchanged files 
+     */
+    private boolean addingNewFiles = false;
 
     /**
      * Encoding to use for filenames, defaults to the platform's
@@ -178,6 +187,7 @@ public class Zip extends MatchingTask {
      */
     public void setUpdate(boolean c) {
         doUpdate = c;
+        savedDoUpdate = c;
     }
 
     /**
@@ -254,13 +264,15 @@ public class Zip extends MatchingTask {
 
     public void execute() throws BuildException {
         if (baseDir == null && filesets.size() == 0
-                && groupfilesets.size() == 0 && "zip".equals(archiveType)) {
-            throw new BuildException( "basedir attribute must be set, or at least " +
-                                      "one fileset must be given!" );
+            && groupfilesets.size() == 0 && "zip".equals(archiveType)) {
+            throw new BuildException( "basedir attribute must be set, "
+                                      + "or at least " 
+                                      + "one fileset must be given!" );
         }
 
         if (zipFile == null) {
-            throw new BuildException("You must specify the " + archiveType + " file to create!");
+            throw new BuildException("You must specify the " 
+                                     + archiveType + " file to create!");
         }
 
         // Renamed version of original file, if it exists
@@ -273,18 +285,21 @@ public class Zip extends MatchingTask {
         if (doUpdate)
         {
             FileUtils fileUtils = FileUtils.newFileUtils();
-            renamedFile = fileUtils.createTempFile("zip", ".tmp",
-                                                   fileUtils.getParentFile(zipFile));
+            renamedFile = 
+                fileUtils.createTempFile("zip", ".tmp",
+                                         fileUtils.getParentFile(zipFile));
 
             try
             {
                 if (!zipFile.renameTo(renamedFile)) {
-                    throw new BuildException("Unable to rename old file to temporary file");
+                    throw new BuildException("Unable to rename old file to "
+                                             + "temporary file");
                 }
             }
             catch (SecurityException e)
             {
-                throw new BuildException("Not allowed to rename old file to temporary file");
+                throw new BuildException("Not allowed to rename old file to "
+                                         + "temporary file");
             }
         }
 
@@ -298,15 +313,17 @@ public class Zip extends MatchingTask {
             File basedir = scanner.getBasedir();
             for (int j=0; j<files.length; j++) {
 
-                log("Adding file " + files[j] + " to fileset", Project.MSG_VERBOSE);
+                log("Adding file " + files[j] + " to fileset", 
+                    Project.MSG_VERBOSE);
                 ZipFileSet zf = new ZipFileSet();
                 zf.setSrc(new File(basedir, files[j]));
                 filesets.addElement(zf);
+                filesetsFromGroupfilesets.addElement(zf);
             }
         }
 
         // Create the scanners to pass to isUpToDate().
-        Vector dss = new Vector ();
+        Vector dss = new Vector();
         if (baseDir != null) {
             dss.addElement(getDirectoryScanner(baseDir));
         }
@@ -318,18 +335,18 @@ public class Zip extends MatchingTask {
         FileScanner[] scanners = new FileScanner[dssSize];
         dss.copyInto(scanners);
 
-        // quick exit if the target is up to date
-        // can also handle empty archives
-        if (isUpToDate(scanners, zipFile)) {
-            return;
-        }
-
-        String action = doUpdate ? "Updating " : "Building ";
-
-        log(action + archiveType +": "+ zipFile.getAbsolutePath());
-
         boolean success = false;
         try {
+            // quick exit if the target is up to date
+            // can also handle empty archives
+            if (isUpToDate(scanners, zipFile)) {
+                return;
+            }
+            
+            String action = doUpdate ? "Updating " : "Building ";
+            
+            log(action + archiveType +": "+ zipFile.getAbsolutePath());
+
             ZipOutputStream zOut =
                 new ZipOutputStream(new FileOutputStream(zipFile));
             zOut.setEncoding(encoding);
@@ -352,22 +369,19 @@ public class Zip extends MatchingTask {
                     ZipFileSet oldFiles = new ZipFileSet();
                     oldFiles.setSrc(renamedFile);
 
-                    StringBuffer exclusionPattern = new StringBuffer();
                     for (int i=0; i < addedFiles.size(); i++)
                     {
-                        if (i != 0) {
-                            exclusionPattern.append(",");
-                        }
-                        exclusionPattern.append((String)addedFiles.elementAt(i));
+                        PatternSet.NameEntry ne = oldFiles.createExclude();
+                        ne.setName((String)addedFiles.elementAt(i));
                     }
-                    oldFiles.setExcludes(exclusionPattern.toString());
-                    Vector tmp = new Vector();
+                    Vector tmp = new Vector(1);
                     tmp.addElement(oldFiles);
                     addFiles(tmp, zOut);
                 }
                 finalizeZipOutputStream(zOut);
 
-                // If we've been successful on an update, delete the temporary file
+                // If we've been successful on an update, delete the
+                // temporary file
                 if (doUpdate) {
                     if (!renamedFile.delete()) {
                         log ("Warning: unable to delete temporary file " +
@@ -382,23 +396,28 @@ public class Zip extends MatchingTask {
                         zOut.close();
                     }
                 } catch(IOException ex) {
-                    // If we're in this finally clause because of an exception, we don't
-                    // really care if there's an exception when closing the stream. E.g. if it
-                    // throws "ZIP file must have at least one entry", because an exception happened
-                    // before we added any files, then we must swallow this exception. Otherwise,
-                    // the error that's reported will be the close() error, which is not the real
-                    // cause of the problem.
+                    // If we're in this finally clause because of an
+                    // exception, we don't really care if there's an
+                    // exception when closing the stream. E.g. if it
+                    // throws "ZIP file must have at least one entry",
+                    // because an exception happened before we added
+                    // any files, then we must swallow this
+                    // exception. Otherwise, the error that's reported
+                    // will be the close() error, which is not the
+                    // real cause of the problem.
                     if (success) {
                         throw ex;
                     }
                 }
             }
         } catch (IOException ioe) {
-            String msg = "Problem creating " + archiveType + ": " + ioe.getMessage();
+            String msg = "Problem creating " + archiveType + ": " 
+                + ioe.getMessage();
 
             // delete a bogus ZIP file
             if (!zipFile.delete()) {
-                msg += " (and the archive is probably corrupt but I could not delete it)";
+                msg += " (and the archive is probably corrupt but I could not "
+                    + "delete it)";
             }
 
             if (doUpdate) {
@@ -429,9 +448,12 @@ public class Zip extends MatchingTask {
      * <p>Ensure parent directories have been added as well.
      */
     protected void addFiles(FileScanner scanner, ZipOutputStream zOut,
-                            String prefix, String fullpath) throws IOException {
+                            String prefix, String fullpath) 
+        throws IOException {
+
         if (prefix.length() > 0 && fullpath.length() > 0) {
-            throw new BuildException("Both prefix and fullpath attributes may not be set on the same fileset.");
+            throw new BuildException("Both prefix and fullpath attributes must"
+                                     + " not be set on the same fileset.");
         }
 
         File thisBaseDir = scanner.getBasedir();
@@ -439,7 +461,9 @@ public class Zip extends MatchingTask {
         // directories that matched include patterns
         String[] dirs = scanner.getIncludedDirectories();
         if (dirs.length > 0 && fullpath.length() > 0) {
-            throw new BuildException("fullpath attribute may only be specified for filesets that specify a single file.");
+            throw new BuildException("fullpath attribute may only be specified"
+                                     + " for filesets that specify a single"
+                                     + " file.");
         }
         for (int i = 0; i < dirs.length; i++) {
             if ("".equals(dirs[i])) {
@@ -455,7 +479,9 @@ public class Zip extends MatchingTask {
         // files that matched include patterns
         String[] files = scanner.getIncludedFiles();
         if (files.length > 1 && fullpath.length() > 0) {
-            throw new BuildException("fullpath attribute may only be specified for filesets that specify a single file.");
+            throw new BuildException("fullpath attribute may only be specified"
+                                     + " for filesets that specify a single"
+                                     + "file.");
         }
         for (int i = 0; i < files.length; i++) {
             File f = new File(thisBaseDir, files[i]);
@@ -476,13 +502,15 @@ public class Zip extends MatchingTask {
     }
 
     protected void addZipEntries(ZipFileSet fs, DirectoryScanner ds,
-                                 ZipOutputStream zOut, String prefix, String fullpath)
+                                 ZipOutputStream zOut, String prefix, 
+                                 String fullpath)
         throws IOException
     {
         log("adding zip entries: " + fullpath, Project.MSG_VERBOSE);
 
         if (prefix.length() > 0 && fullpath.length() > 0) {
-            throw new BuildException("Both prefix and fullpath attributes may not be set on the same fileset.");
+            throw new BuildException("Both prefix and fullpath attributes must"
+                                     + " not be set on the same fileset.");
         }
 
         ZipScanner zipScanner = (ZipScanner) ds;
@@ -504,7 +532,8 @@ public class Zip extends MatchingTask {
                     } else {
                         addParentDirs(null, vPath, zOut, prefix);
                         if (! entry.isDirectory()) {
-                            zipFile(in, zOut, prefix+vPath, entry.getTime(), zipSrc);
+                            zipFile(in, zOut, prefix+vPath, entry.getTime(), 
+                                    zipSrc);
                         }
                     }
                 }
@@ -535,37 +564,46 @@ public class Zip extends MatchingTask {
         // In this case using java.util.zip will not work
         // because it does not permit a zero-entry archive.
         // Must create it manually.
-        log("Note: creating empty "+archiveType+" archive " + zipFile, Project.MSG_INFO);
+        log("Note: creating empty "+archiveType+" archive " + zipFile, 
+            Project.MSG_INFO);
+        OutputStream os = null;
         try {
-            OutputStream os = new FileOutputStream(zipFile);
-            try {
-                // Cf. PKZIP specification.
-                byte[] empty = new byte[22];
-                empty[0] = 80; // P
-                empty[1] = 75; // K
-                empty[2] = 5;
-                empty[3] = 6;
-                // remainder zeros
-                os.write(empty);
-            } finally {
-                os.close();
-            }
+            os = new FileOutputStream(zipFile);
+            // Cf. PKZIP specification.
+            byte[] empty = new byte[22];
+            empty[0] = 80; // P
+            empty[1] = 75; // K
+            empty[2] = 5;
+            empty[3] = 6;
+            // remainder zeros
+            os.write(empty);
         } catch (IOException ioe) {
-            throw new BuildException("Could not create empty ZIP archive", ioe, location);
+            throw new BuildException("Could not create empty ZIP archive "
+                                     + "(" + ioe.getMessage() + ")", ioe, 
+                                     location);
+        } finally {
+            if (os != null) {
+                try {
+                    os.close();
+                } catch (IOException e) {
+                }
+            }
         }
         return true;
     }
 
 
     /**
-     * Check whether the archive is up-to-date; and handle behavior for empty archives.
+     * Check whether the archive is up-to-date; and handle behavior
+     * for empty archives.
      * @param scanners list of prepared scanners containing files to archive
      * @param zipFile intended archive file (may or may not exist)
-     * @return true if nothing need be done (may have done something already); false if
-     *         archive creation should proceed
+     * @return true if nothing need be done (may have done something
+     *         already); false if archive creation should proceed
      * @exception BuildException if it likes
      */
-    protected boolean isUpToDate(FileScanner[] scanners, File zipFile) throws BuildException
+    protected boolean isUpToDate(FileScanner[] scanners, File zipFile) 
+        throws BuildException
     {
         String[][] fileNames = grabFileNames(scanners);
         File[] files = grabFiles(scanners, fileNames);
@@ -575,7 +613,8 @@ public class Zip extends MatchingTask {
                     " because no files were included.", Project.MSG_WARN);
                 return true;
             } else if (emptyBehavior.equals("fail")) {
-                throw new BuildException("Cannot create "+archiveType+" archive " + zipFile +
+                throw new BuildException("Cannot create "+archiveType
+                                         +" archive " + zipFile +
                                          ": no files were included.", location);
             } else {
                 // Create.
@@ -584,12 +623,13 @@ public class Zip extends MatchingTask {
         } else {
             for (int i = 0; i < files.length; ++i) {
                 if (files[i].equals(zipFile)) {
-                    throw new BuildException("A zip file cannot include itself", location);
+                    throw new BuildException("A zip file cannot include itself", 
+                                             location);
                 }
             }
 
             if (!zipFile.exists()) {
-              return false;
+                return false;
             }
 
             SourceFileScanner sfs = new SourceFileScanner(this);
@@ -677,12 +717,15 @@ public class Zip extends MatchingTask {
             }
             else if (duplicate.equals("fail"))
             {
-                throw new BuildException("Duplicate file " + vPath + " was found and the duplicate attribute is 'fail'.");
+                throw new BuildException("Duplicate file " + vPath 
+                                         + " was found and the duplicate "
+                                         + "attribute is 'fail'.");
             }
             else
             {
                 // duplicate equal to add, so we continue
-                log("duplicate file " + vPath + " found, adding.", Project.MSG_VERBOSE);
+                log("duplicate file " + vPath 
+                    + " found, adding.", Project.MSG_VERBOSE);
             }
         }
         else
@@ -754,7 +797,8 @@ public class Zip extends MatchingTask {
         throws IOException
     {
         if (file.equals(zipFile)) {
-            throw new BuildException("A zip file cannot include itself", location);
+            throw new BuildException("A zip file cannot include itself", 
+                                     location);
         }
 
         FileInputStream fIn = new FileInputStream(file);
@@ -859,6 +903,14 @@ public class Zip extends MatchingTask {
         addedDirs.clear();
         addedFiles.removeAllElements();
         entries.clear();
+        addingNewFiles = false;
+        doUpdate = savedDoUpdate;
+        Enumeration enum = filesetsFromGroupfilesets.elements();
+        while (enum.hasMoreElements()) {
+            ZipFileSet zf = (ZipFileSet) enum.nextElement();
+            filesets.removeElement(zf);
+        }
+        filesetsFromGroupfilesets.removeAllElements();
     }
 
     /**
@@ -880,7 +932,6 @@ public class Zip extends MatchingTask {
         emptyBehavior = "skip";
         doUpdate = false;
         doFilesonly = false;
-        addingNewFiles = false;
         encoding = null;
     }