Fix regression in repeated -d of the same change.
Fix regression in repeated -d of the same change.

Fixes bug 1092943.

* git-review(download_review): Earlier refactoring in commit 4511318
resulted in checking the wrong output for existing branch errors,
since it moved into the exception data. Fixed in this commit.

Change-Id: I761b01c70ab93e77b112ddf85c63a829d5334196

openstack-infra/git-review,entropia1/git-review,meelapshah/git-review,meelapshah/git-review,ka2m/git-review,jeeloo/git-review