Add a test case for the UnversionedUnexpected file code path.

TEST=This test case will catch the bug fixed by r26425.
BUG=none

Patch contributed by msb@

Review URL: http://codereview.chromium.org/214005


git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@26458 0039d316-1c4b-4281-b951-d872f2087c98