Fixes #27904

Change-Id: Ie2aad20cd66785b6cc1018c0048824382cb39f8c
Reviewed-on: https://go-review.googlesource.com/c/140158
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>