git-codereview: fix missing upstream detection

With git 2.4.3, the current tests fail (and it breaks in real use):

$ go test
git rev-parse --abbrev-ref newbranch@{u}
fatal: no upstream configured for branch 'newbranch'

git-codereview: exit status 128
exit status 1
FAIL	golang.org/x/review/git-codereview	0.361s
$

The message changed from "No" to "no". Fix detection.

Change-Id: I814a7cec612fc12496ef89ccfd80fb70c09d4e46
Reviewed-on: https://go-review.googlesource.com/11172
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

0 files changed, 0 insertions, 0 deletions