WFCORE-129 - overlay does not work for zipped files in exploded archive

WFLY: https://issues.jboss.org/browse/WFCORE-129
6.4.0: https://bugzilla.redhat.com/show_bug.cgi?id=1147352
This will result in the overlay being mounted in the wrong place. Say you have an overlay for /a/b/c/contentst.txt and only /a exists. The loop above will result in parent being set to /a, then the isDirectory check will pass an you will end up with /a/contents.txt being mounted.