Update #14559.

Change-Id: I8894f8e16902685f55a21d902199fbe0905f0558
Reviewed-on: https://go-review.googlesource.com/20050
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>