[1.7.x] Fixed flake8 errors.

Backport of fddd95254e from master

django/utils/autoreload.py

@@ -80,6 +80,7 @@ _error_files = []
 _cached_modules = set()
 _cached_filenames = []
 
+
 def gen_filenames(only_new=False):
     """
     Returns a list of filenames referenced in sys.modules and translation

tests/utils_tests/test_autoreload.py

@@ -76,8 +76,8 @@ class TestFilenameGenerator(TestCase):
         When calling a second time gen_filenames with only_new = True, only
         files from newly loaded modules should be given.
         """
-        filenames1 = list(gen_filenames())
-        from fractions import Fraction
+        list(gen_filenames())
+        from fractions import Fraction  # NOQA
         filenames2 = list(gen_filenames(only_new=True))
         self.assertEqual(len(filenames2), 1)
         self.assertTrue(filenames2[0].endswith('fractions.py'))