Fix up some pytest-related stuff (#601)

diff --git a/tests/test_crypto.py b/tests/test_crypto.py
index ad79f6a..878479f 100644
--- a/tests/test_crypto.py
+++ b/tests/test_crypto.py
@@ -743,9 +743,7 @@
 
 class TestPKey(object):
     """
-    py.test-based tests for :class:`OpenSSL.crypto.PKey`.
-
-    If possible, add new tests here.
+    Tests for `OpenSSL.crypto.PKey`.
     """
 
     def test_convert_from_cryptography_private_key(self):