The messages contain no format string, so there is no need to use
t.Fatalf.

Change-Id: I29098c04797f919784b732af84a63fbaed671558
Reviewed-on: https://go-review.googlesource.com/111776
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>