It looks like crypt.crypt('', crypt.METHOD_CRYPT) returns None. This method must be excluded from crypt.methods. Attached patch should fix the issue, but I didn't try it on OpenBSD.

Python 3.4-3.6 is affect, Python 2.7 is not affect (crypt.methods was introduced in Python 3).

http://buildbot.python.org/all/builders/x86%20OpenBSD%203.5/builds/186/steps/test/logs/stdio

test_saltedcrypt (test.test_crypt.CryptTestCase) ... ERROR

======================================================================
ERROR: test_saltedcrypt (test.test_crypt.CryptTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/python-builds/3.5.borja-openbsd-x86/build/Lib/test/test_crypt.py", line 23, in test_saltedcrypt
    self.assertEqual(len(pw), method.total_size)
TypeError: object of type 'NoneType' has no len()

----------------------------------------------------------------------