Fixes #19695

Change-Id: Ie5103f7905969e25dba6e5fb37344b70e807fc69
Reviewed-on: https://go-review.googlesource.com/45702
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>