revision may be null

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@277977 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/taskdefs/cvslib/CvsTagDiff.java

@@ -411,7 +411,9 @@ public class CvsTagDiff extends AbstractCvsTask {
         Element ent = doc.createElement("entry");
         Element f = DOMUtils.createChildElement(ent, "file");
         DOMUtils.appendCDATAElement(f, "name", entry.getFile());
-        DOMUtils.appendTextElement(f, "revision", entry.getRevision());
+        if (entry.getRevision() != null) {
+            DOMUtils.appendTextElement(f, "revision", entry.getRevision());
+        }
         if (entry.getPreviousRevision() != null) {
             DOMUtils.appendTextElement(f, "prevrevision",
                                        entry.getPreviousRevision());