For some reason "--tags" wasn't working on some versions of git (pre-1.9)

BUG=339171

Review URL: https://codereview.chromium.org/183813004

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@253929 0039d316-1c4b-4281-b951-d872f2087c98