Updates #18581
Updates #20858

Change-Id: I6b5ce0e255a42c028d46815fff5a5aca68690fd9
Reviewed-on: https://go-review.googlesource.com/47254
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>