When using a raw URL from a different Rietveld instance than the one
in codereview.settings, you get an error like this:

File "depot_tools/git_cl.py", line 2767, in PatchIssue
    RunGit(['commit', '-m', (cl.GetDescription() + '\n\n' +
UnboundLocalError: local variable 'cl' referenced before assignment

This fixes that. It is needed for the WebRTC transition to the
Chromium Rietveld instance using https://codereview.webrtc.org

BUG=webrtc:3884
TESTED=In a WebRTC checkout: ran 'git cl patch https://codereview.webrtc.org/download/issue1135893005_1.diff'
on a clean branch and had it apply correctly.
In a Chromium checkout, ran 'git cl patch 1154023002' and verified
the commit message was correct.
I also ran using the raw URL and verified the result was the same.

Review URL: https://codereview.chromium.org/1166673002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@295491 0039d316-1c4b-4281-b951-d872f2087c98