Fixes #29517

Change-Id: I7e741d82bb9f8e6ab39b6d9ab37ba6163176a097
GitHub-Last-Rev: 764d0bd9579cd90868c6a134cbb06dda584474d7
GitHub-Pull-Request: golang/go#29519
Reviewed-on: https://go-review.googlesource.com/c/156118Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>