code: protected void cleanUp()
          throws IOException
      {
          super.cleanUp();
  
          // we want to save this info if we are going to make another pass
          if ( !doubleFilePass || !skipWriting )
          {
              manifest = null;
              configuredManifest = savedConfiguredManifest;
              filesetManifest = null;
              originalManifest = null;
          }
          rootEntries.removeAllElements();
      }
docs: Make sure we don't think we already have a MANIFEST next time this task
  gets executed.
  
  @see ZipArchiver#cleanUp