Fixes #29271

Change-Id: Iff6a16c659ad6ec1b4d9559fcbcd40196086c60e
Reviewed-on: https://go-review.googlesource.com/c/154380
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>