Replace equals None with is None

None is a singleton and should be tested for with is not ==.

Some people did a similar thing randomly on the master branch. It
just seems like a thing we should fix.

Change-Id: Iec0382e2c8812f0713699ab5a0cd3180086ad433
diff --git a/tests/unit/test_scheduler.py b/tests/unit/test_scheduler.py
index f5c181b..a1a1134 100755
--- a/tests/unit/test_scheduler.py
+++ b/tests/unit/test_scheduler.py
@@ -3536,9 +3536,9 @@
         self.assertEqual([], running_item['failing_reasons'])
         self.assertEqual([], running_item['items_behind'])
         self.assertEqual('https://hostname/1', running_item['url'])
-        self.assertEqual(None, running_item['item_ahead'])
+        self.assertIsNone(running_item['item_ahead'])
         self.assertEqual('org/project', running_item['project'])
-        self.assertEqual(None, running_item['remaining_time'])
+        self.assertIsNone(running_item['remaining_time'])
         self.assertEqual(True, running_item['active'])
         self.assertEqual('1,1', running_item['id'])
 
@@ -3553,7 +3553,7 @@
                 self.assertEqual(7, len(job['worker']))
                 self.assertEqual(False, job['canceled'])
                 self.assertEqual(True, job['voting'])
-                self.assertEqual(None, job['result'])
+                self.assertIsNone(job['result'])
                 self.assertEqual('gate', job['pipeline'])
                 break