Updates #17937

Change-Id: Ic822da1786a983b3b7bca21b68c3d5fc4bdfaee2
Reviewed-on: https://go-review.googlesource.com/33428
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>