In lieu of the more invasive https://go-review.googlesource.com/#/c/12373/ .

Change-Id: I0221783fcaa8af04520c80cd2993d7d542d2c431
Reviewed-on: https://go-review.googlesource.com/12486Reviewed-by: Alan Donovan <adonovan@google.com>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>