overcloud using 7-director is deployed successfully.

Upgrade overcloud to 8 shows "CREATE_FAILED" after deploy:

[stack@instack ~]$ source stackrc 
[stack@instack ~]$ heat stack-list
+--------------------------------------+------------+---------------+---------------------+---------------------+
| id                                   | stack_name | stack_status  | creation_time       | updated_time        |
+--------------------------------------+------------+---------------+---------------------+---------------------+
| ed43e592-6f0b-4230-ab7a-a03d33c72ab9 | overcloud  | UPDATE_FAILED | 2016-03-23T23:16:40 | 2016-03-24T00:37:40 |
+--------------------------------------+------------+---------------+---------------------+---------------------+


This is in heat-engine.log on undercloud:
deploy_status_code: Deployment exited with non-zero status code: 6