Deployment fails when deploying multiple overcloud nodes

Issue

• Under certain circumstances, overcloud nodes can fail to deploy when there are multiple nodes being deployed simultaneously. This is due to a race condition between nova and ironic.

The error message in the logs will be as below.

2015-08-28 12:52:03.004 1695 WARNING wsme.api [-] Client-side error: Node 4c8a48d4-de85-4133-bc25-b0be2b7cd83a is associated with instance 45797815-cd88-4a77-bd93-f323a7f74544.
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/dispatcher.py", line 142, in _dispatch_and_reply
    executor_callback))
  File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/dispatcher.py", line 186, in _dispatch
    executor_callback)
  File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/dispatcher.py", line 130, in _do_dispatch
    result = func(ctxt, **new_args)
  File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/server.py", line 142, in inner
    return func(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/ironic/conductor/manager.py", line 405, in update_node
    node_obj.save()
  File "/usr/lib/python2.7/site-packages/ironic/objects/base.py", line 143, in wrapper
    return fn(self, ctxt, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/ironic/objects/node.py", line 265, in save
    self.dbapi.update_node(self.uuid, updates)
  File "/usr/lib/python2.7/site-packages/ironic/db/sqlalchemy/api.py", line 338, in update_node
    return self._do_update_node(node_id, values)
  File "/usr/lib/python2.7/site-packages/ironic/db/sqlalchemy/api.py", line 364, in _do_update_node
    instance=ref.instance_uuid)
NodeAssociated: Node 4c8a48d4-de85-4133-bc25-b0be2b7cd83a is associated with instance 45797815-cd88-4a77-bd93-f323a7f74544.