Updates #20587

Change-Id: I08377281270631ee08cd05ba835aa698ca23fa56
Reviewed-on: https://go-review.googlesource.com/47092
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>