Consistently use REBUILDING vm_state

There is both a vm_state and task_state called REBUILDING, which was
used inconsistently. This resulted in a rebuild action returning
"ACTIVE" for the status instead of "REBUILD" like the API
documentation states.

This change drops the task_state in favor of making all of the code
use vm_state

Change-Id: I56b4b6fd4d02b75c6270fc91cdec1902e7794cf1

nova/compute/api.py

@@ -1210,8 +1210,8 @@ class API(base.Base):
                     metadata=metadata,
                     display_name=name,
                     image_ref=image_href,
-                    vm_state=vm_states.ACTIVE,
-                    task_state=task_states.REBUILDING,
+                    vm_state=vm_states.REBUILDING,
+                    task_state=None,
                     progress=0)
 
         rebuild_params = {

nova/compute/task_states.py

@@ -43,8 +43,6 @@ RESIZE_REVERTING = 'resize_reverting'
 RESIZE_CONFIRMING = 'resize_confirming'
 RESIZE_VERIFY = 'resize_verify'
 
-REBUILDING = 'rebuilding'
-
 REBOOTING = 'rebooting'
 REBOOTING_HARD = 'rebooting_hard'
 PAUSING = 'pausing'

nova/tests/test_compute.py

@@ -1600,7 +1600,7 @@ class ComputeAPITestCase(BaseTestCase):
         self.compute_api.rebuild(self.context, instance, image_ref, password)
 
         instance = db.instance_get_by_uuid(self.context, instance_uuid)
-        self.assertEqual(instance['task_state'], task_states.REBUILDING)
+        self.assertEqual(instance['vm_state'], vm_states.REBUILDING)
 
         db.instance_destroy(self.context, instance_uuid)