Follow-up to CL 26661

Change-Id: I67c58d17313094675cf0f30ce50d486818ae0dcb
Reviewed-on: https://go-review.googlesource.com/27113
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>