acme: fix mismatched format arguments in acme_test.go

Change-Id: I4d685309e375fd0bb50d1d32c60ac48a7f2515fc
Reviewed-on: https://go-review.googlesource.com/47358
Run-TryBot: Alex Vaghin <ddos@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Vaghin <ddos@google.com>
1 file changed