Fixes #20796
Fixes #16283

Change-Id: Ib11992fbd2bc1fbb3b14ae5a6bf0da2e4c12f641
Reviewed-on: https://go-review.googlesource.com/49311Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>