Always update remote_stack

Always update remote_stack even though properties didn't change,
and let the let the individual resources in it decide if they
need updating

Closes-Bug: #1428979
Change-Id: Id0898683b86e3a72e539f2432f521c7ee70afe26

heat/engine/resources/openstack/heat/remote_stack.py

@@ -192,7 +192,9 @@ class RemoteStack(resource.Resource):
         return True
 
     def handle_update(self, json_snippet, tmpl_diff, prop_diff):
-        if self.resource_id and prop_diff:
+        # Always issue an update to the remote stack and let the individual
+        # resources in it decide if they need updating.
+        if self.resource_id:
             snippet = json_snippet.get('Properties', {})
             self.properties = properties.Properties(self.properties_schema,
                                                     snippet,

heat/tests/test_remote_stack.py

@@ -575,6 +575,24 @@ class RemoteStackTest(tests_common.HeatTestCase):
         self.assertEqual((rsrc.UPDATE, rsrc.FAILED), rsrc.state)
         self.assertEqual(2, len(self.heat.stacks.get.call_args_list))
 
+    def test_update_no_change(self):
+        stacks = [get_stack(stack_status='UPDATE_IN_PROGRESS'),
+                  get_stack(stack_status='UPDATE_COMPLETE')]
+
+        def side_effect(*args, **kwargs):
+            return stacks.pop(0)
+
+        rsrc = self.create_remote_stack()
+
+        props = copy.deepcopy(rsrc.parsed_template()['Properties'])
+        update_snippet = rsrc_defn.ResourceDefinition(rsrc.name,
+                                                      rsrc.type(),
+                                                      props)
+
+        self.heat.stacks.get = mock.MagicMock(side_effect=side_effect)
+        scheduler.TaskRunner(rsrc.update, update_snippet)()
+        self.assertEqual((rsrc.UPDATE, rsrc.COMPLETE), rsrc.state)
+
     def test_stack_status_error(self):
         returns = [get_stack(stack_status='DELETE_IN_PROGRESS'),
                    get_stack(stack_status='UPDATE_COMPLETE')]