Fix git cl comments when there's no issue associated with the current branch.
Fix git cl comments when there's no issue associated with the current branch.

It currently crashes, which is sad.

R=pgervais@chromium.org
BUG=

Review URL: https://codereview.chromium.org/683283006

git-svn-id: bd64dd6fa6f3f0ed0c0666d1018379882b742947@292899 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

svn2github/chromium-depot-tools,svn2github/chromium-depot-tools,svn2github/chromium-depot-tools