Beautify error message.

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@530818 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/taskdefs/ManifestTask.java

@@ -146,7 +146,7 @@ public class ManifestTask extends Task {
         char ch = name.charAt(0);
 
         if (ch == '-' || ch == '_') {
-            throw new BuildException("Manifest attribute names must not contain '" + ch + "' at the begin.");
+            throw new BuildException("Manifest attribute names must not start with '" + ch + "'.");
         }
         
         for (int i = 0; i < name.length(); i++) {

src/tests/junit/org/apache/tools/ant/taskdefs/ManifestTest.java

@@ -341,7 +341,7 @@ public class ManifestTest extends BuildFileTest {
     }
 
     public void testIllegalNameBegin() {
-        expectBuildException("testIllegalNameInSection", "Manifest attribute names must not contain '-' at the begin.");
+        expectBuildException("testIllegalNameInSection", "Manifest attribute names must not start with '-' at the begin.");
     }
 
     public void testIllegalName2() {