exec task outputted two redundant trailing newlines

PR: 27546
Reported by: marcel at schutte dot com
Obtained from: Martijn Kruithof


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@276221 13f79535-47bb-0310-9956-ffa450edef68

WHATSNEW

@@ -71,6 +71,10 @@ Fixed bugs:
 
 * if the basedir contained .. or . dirs, and the build file name contained
   .. or ., the basedir was set incorrectly. Bugzilla Report 26765.
+
+* regression from ant 1.5, exec task outputted two redundant trailing newlines.
+  Bugzilla Report 27546.
+
 Other changes:
 --------------
 

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

@@ -85,7 +85,9 @@ public class LogOutputStream extends OutputStream {
      * Flush this log stream
      */
     public void flush() {
-       processBuffer();
+        if (buffer.size() > 0) {
+            processBuffer();
+        }
     }