clear out buffer so the last block is always filled with EOF records. PR 47421

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@789556 13f79535-47bb-0310-9956-ffa450edef68

WHATSNEW

@@ -388,6 +388,10 @@ Fixed bugs:
  * <loadproperties>' encoding attribute didn't work.
    Bugzilla Report 47382.
 
+ * Ant created tar archives could contain random bytes at the end
+   which confused some untar implementations.
+   Bugzilla Report 47421.
+
 Other changes:
 --------------
  * A HostInfo task was added performing information on hosts, including info on 

src/main/org/apache/tools/tar/TarBuffer.java

@@ -412,6 +412,7 @@ public class TarBuffer {
 
         currRecIdx = 0;
         currBlkIdx++;
+        Arrays.fill(blockBuffer, (byte) 0);
     }
 
     /**