git-codereview: fix test regressions in TestMail*

Commit 8ef20ce (set x.mailed tag to mailed commit instead of HEAD) broke
TestMail, TestMailShort, and TestMailTopic.

Possibly related to golang/go#9602.

Change-Id: Iac5ea98d034ee4815b3b7ea2d5cc3f523944b953
Reviewed-on: https://go-review.googlesource.com/9312
Reviewed-by: Andrew Gerrand <adg@golang.org>
1 file changed