crypto test failures on debian/kfreebsd.

[David Bremner]

0.17~rc1 is failing several crypto tests on debian/kfreebsd [1]


 FAIL   signature verification
	--- crypto.2.expected	2013-11-24 04:17:13.000000000 +0000
	+++ crypto.2.output	2013-11-24 04:17:13.000000000 +0000
	@@ -11,7 +11,7 @@
	                                 "id": 2
	                             },
	                             {
	-                                "content-length": 315,
	+                                "content-length": 318,
	                                 "content-type": "application/pgp-signature",
	                                 "id": 3
	                             }


According to dkg's nifty printmimestructure script, the result computed
by notmuch is actually correct. So it looks like different environments
result in different content-length headers. I'm not sure if this is a
bug that should be tracked down, or we should just sanitize the test
data more.

[1]: https://buildd.debian.org/status/fetch.php?pkg=notmuch&arch=kfreebsd-i386&ver=0.17%7Erc1-1&stamp=1385266740