The codereview command will start using this to figure out
the origin branch for commands like "git pending",
and it will use the parent setting for the new "git branch-sync" (merge).
Change-Id: Ia74af18ae5a437fb45ea81d7d69e2ffe41987b64
Reviewed-on: https://go-review.googlesource.com/c/go/+/279523
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
