Update #4339.

Change-Id: Ic1a7535562b8b824ba166777725f7ba5b9623d77
Reviewed-on: https://go-review.googlesource.com/8523
Run-TryBot: Minux Ma <minux@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>