There this job was originally misconfigured and was configured as if
it was a verify job. It should be operating instead as a merge job
and not be pulling in the $sha1 setting. This fixes the job to only
build HEAD of branch as one would expect.
Issue: RELENG-844
Change-Id: I8fa6b25a2fd4b598f619ab4c6ae80ce411756cb4 Signed-off-by: Thanh Ha <thanh.ha@linuxfoundation.org>