Fixes some failing Google tests when run under Go tip (1.6).

Updates #12986

Change-Id: I0ca4d20f6103d10ea9464e45730085401336dada
Reviewed-on: https://go-review.googlesource.com/17698Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Nodir Turakulov <nodir@google.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>