Update golang/go#9327.

Change-Id: Iab7dad31cf6b9f9347c3f34faebb67ecb38b17fc
Reviewed-on: https://go-review.googlesource.com/16701
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>