Fixed a few more imports of django.utils.unittest.

One import per line please! Refs #20680.

tests/utils_tests/test_feedgenerator.py

@@ -1,8 +1,11 @@
 from __future__ import unicode_literals
 
 import datetime
+import unittest
+
+from django.utils import feedgenerator
+from django.utils import tzinfo
 
-from django.utils import feedgenerator, tzinfo, unittest
 
 class FeedgeneratorTest(unittest.TestCase):
     """