Reset task state before rescheduling

Reset the task state to SCHEDULING before attempting re-scheduling.
This is a precaution to make sure subsequent calls to update the
task state see an 'expected_task_state'.

bug 1049897

Change-Id: I5667a88487bd7039eb2e0aaebef532199d8b31ef

nova/compute/manager.py

@@ -569,6 +569,11 @@ def _reschedule(self, context, instance_uuid, requested_networks,
 
         LOG.debug(_("Re-scheduling instance: attempt %d"),
                   retry['num_attempts'], instance_uuid=instance_uuid)
+
+        # reset the task state:
+        self._instance_update(context, instance_uuid,
+                task_state=task_states.SCHEDULING)
+
         self.scheduler_rpcapi.run_instance(context,
                 request_spec, admin_password, injected_files,
                 requested_networks, is_first_time, filter_properties)

nova/tests/compute/test_compute.py

@@ -5038,6 +5038,10 @@ def setUp(self):
 
         self._reschedule = self._reschedule_partial()
 
+        def fake_update(*args, **kwargs):
+            self.updated_task_state = kwargs.get('task_state')
+        self.stubs.Set(self.compute, '_instance_update', fake_update)
+
     def _reschedule_partial(self):
         uuid = "12-34-56-78-90"
 
@@ -5072,6 +5076,7 @@ def test_reschedule_success(self):
         self.assertTrue(self._reschedule(filter_properties=filter_properties,
             request_spec=request_spec))
         self.assertEqual(1, len(request_spec['instance_uuids']))
+        self.assertEqual(self.updated_task_state, task_states.SCHEDULING)
 
 
 class ThatsNoOrdinaryRabbitException(Exception):