Fixes #19647

Change-Id: Ife4f98cf2c55ee9490843797213dae2f2647b0a3
Reviewed-on: https://go-review.googlesource.com/40577Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>