Fixes #11763

Change-Id: Ie291b36a8c29694e80940836d7e6fd96d2d76494
Reviewed-on: https://go-review.googlesource.com/12382Reviewed-by: Mikio Hara <mikioh.mikioh@gmail.com>
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>