While we're here, use test[%d] in place of #%d.

Change-Id: Ie30afcab9673e78d3ea7ca80f5e662fbea897488
Reviewed-on: https://go-review.googlesource.com/31936
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>