- gerrit create branch endpoint returns code 201 instead of 200

Bug:
R=agable

Change-Id: I07697e87e506d5545e9abd501775e0fc30a48f80
Reviewed-on: https://chromium-review.googlesource.com/482522Reviewed-by: Aaron Gable <agable@chromium.org>
Commit-Queue: Di Mu <dimu@chromium.org>