Missed in CL 49253 because I submitted from the Gerrit UI and
had not mailed the latest copy. Sigh.

Change-Id: I540f960278df43e2eaf1aac188eb124a1ff240dd
Reviewed-on: https://go-review.googlesource.com/49256
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>