Updates #16357.

Change-Id: I37f04d83134b5e1e7f6ba44eb9a566758ef594d3
Reviewed-on: https://go-review.googlesource.com/29350
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>