r176777 introduced a change that relied on os.path.samepath, which does not exist on Windows.

BUG=


Review URL: https://chromiumcodereview.appspot.com/12021013

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@177701 0039d316-1c4b-4281-b951-d872f2087c98