HADOOP-8847 originally introduced this change on branch-1-win. HADOOP-9081 ported the change to branch-trunk-win. This should be simple to port to trunk, which would simplify the merge and test activity happening on HADOOP-8562.
Enhancements to support Hadoop on Windows Server and Windows Azure environments
Change untar to use Java API on Windows instead of spawning tar process
Port TestWinUtils from branch-1-win to branch-trunk-win