SM provision failure in provision_control.py

Seen in CB R4.1-50 newton:

+----------+---------------------+------------+--------------------------------------------------------------------------+
| id | status | ip_address | roles |
+----------+---------------------+------------+--------------------------------------------------------------------------+
| server4 | provision_failed | 10.0.0.7 | [u'contrail-controller', u'contrail-analytics', u'contrail-analyticsdb'] |
| server6 | provision_failed | 10.0.0.9 | [u'contrail-controller', u'contrail-analytics', u'contrail-analyticsdb'] |
| server7 | provision_failed | 10.0.0.10 | [u'contrail-lb'] |
| server1 | provision_completed | 10.0.0.4 | [u'openstack'] |
| server2 | provision_completed | 10.0.0.5 | [u'openstack'] |
| server3 | provision_completed | 10.0.0.6 | [u'openstack'] |
| server10 | provision_failed | 10.0.0.13 | [u'contrail-compute'] |
| server5 | provision_failed | 10.0.0.8 | [u'contrail-controller', u'contrail-analytics', u'contrail-analyticsdb'] |
| server8 | provision_failed | 10.0.0.11 | [u'contrail-compute'] |
| server9 | provision_failed | 10.0.0.12 | [u'contrail-compute'] |
+----------+---------------------+------------+--------------------------------------------------------------------------+

"2017-11-16 09:54:15,514-INFO-sm_ansible_callback.py:53-append(): fatal: [10.0.0.9]Traceback (most recent call last):
  File "/usr/share/contrail-utils/provision_control.py", line 225, in <module>
    main()
  File "/usr/share/contrail-utils/provision_control.py", line 221, in main
    ControlProvisioner(args_str)
  File "/usr/share/contrail-utils/provision_control.py", line 64, in __init__
    self._args.address_families, self._args.md5)
  File "/usr/share/contrail-utils/provision_bgp.py", line 107, in add_bgp_router
    cur_id = vnc_lib.bgp_router_create(bgp_router_obj)
  File "/usr/lib/python2.7/dist-packages/vnc_api/vnc_api.py", line 42, in wrapper
    return func(self, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/vnc_api/vnc_api.py", line 483, in _object_create
    rest.OP_POST, obj_cls.create_uri, data=json_body)
  File "/usr/lib/python2.7/dist-packages/vnc_api/vnc_api.py", line 872, in _request_server
    retry_after_authn=retry_after_authn, retry_count=retry_count)
  File "/usr/lib/python2.7/dist-packages/vnc_api/vnc_api.py", line 962, in _request
    raise RefsExistError(content)
cfgm_common.exceptions.RefsExistError: ['default-domain', 'default-project', 'ip-fabric', '__default__', 'server4'] already exists with uuid: 75ae2f55-1cb9-48c9-901a-b5302d4cad70"
"2017-11-16 09:54:15,532-INFO-sm_ansible_callback.py:53-append(): changed: [10.0.0.7] => (item={'key': u'10.10.0.7', 'value': u'server4'})"
"2017-11-16 09:54:15,669-INFO-sm_ansible_callback.py:53-append(): changed: [10.0.0.8] => (item={'key': u'10.10.0.7', 'value': u'server4'})"
"2017-11-16 09:54:16,724-INFO-sm_ansible_callback.py:53-append(): fatal: [10.0.0.7]Traceback (most recent call last):