No code changes.

Fixes #8992

Change-Id: I10c8340a4f8e3e7add9b3ac5aa0a1e8d8aa49f40
Reviewed-on: https://go-review.googlesource.com/9412Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>