Upgrade fails from 2.0.0->2.0.1

The new image doesn't have an existing old image, so it
ends up not existing.  In this condition, we know that
we are dealing with a version change upgrade.

TrivialFix

Change-Id: Ic2f83c2bb6c34731b60b3430ba66a6324439f0a9

ansible/library/kolla_docker.py

@@ -274,6 +274,8 @@ class DockerWorker(object):
             return True
         new_image = self.check_image()
         current_image = container_info['Image']
+        if not new_image:
+            return True
         if new_image['Id'] != current_image:
             return True