FIX/UPD: tests are OK with python3.

dav_base/tests/generic.py

@@ -72,7 +72,7 @@ class EmailTestMixin(object):
             try:
                 self.assertEqual(line, expected_line)
             except AssertionError as e:
-                self.fail('line %d: %s' % (i, e.message))
+                self.fail('line %d: %s' % (i, e))
         self.assertEqual(mail.body, body)
 
     def setUp(self):