Updated test for p-u 3.0.21

Author: krosenvold

src/test/java/org/codehaus/plexus/archiver/BasePlexusArchiverTest.java

@@ -57,6 +57,7 @@ protected void waitUntilNewTimestamp( File outputFile, long timestampReference )
         while ( timestampReference >= outputFile.lastModified() )
         {
             FileUtils.copyFile( tmpFile, outputFile );
+            outputFile.setLastModified(System.currentTimeMillis());
             Thread.yield();
         }