Fixes #19415

Change-Id: I6414f82e42bd09f1793156befce326aeac919ea2
Reviewed-on: https://go-review.googlesource.com/37911Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>