Fix docker container restart

restart_containers(containers.running) may try to restart containers
that are deleted when looping through get_differing_containers()
fix this by refreshing list after first loop

cloud/docker/docker.py

@@ -1729,6 +1729,8 @@ def restarted(manager, containers, count, name):
         manager.stop_containers([container])
         manager.remove_containers([container])
 
+    containers.refresh()
+
     manager.restart_containers(containers.running)
     started(manager, containers, count, name)