Fixes #28169

Change-Id: I187d9effea56357bbb04d4971d284a52ffae61f8
Reviewed-on: https://go-review.googlesource.com/c/142889
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>