Updates #13560

Change-Id: I9bc08ca5cf0627e653d55f748ebb83be8b69ea3b
Reviewed-on: https://go-review.googlesource.com/39296
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>