Fixes #15246
Re-opens #14969

Change-Id: Ic0b41c5aa42bbb229a0d62b7f3e5888c6b29293d
Reviewed-on: https://go-review.googlesource.com/21891
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>