Fixes #29627

Change-Id: I08a5b45151a11b5a4f3b5a2d984c0322cf904697
Reviewed-on: https://go-review.googlesource.com/c/157098
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>