Comment 9 for bug 1446202

Guys, looks like we have problem in other place. I've checked logic and looks like original reason is this:

2015-04-20 04:17:14.036 INFO [7f2b1f8ae700] (receiver) RPC method remove_nodes_resp received: {"status": "ready", "progress": 100, "task_uuid": "5c7cfc4a-91ae-449b-8fb4-7745b2998839", "nodes": [{"uid": "7"}, {"uid": "3"}]}
2015-04-20 04:17:15.119 ERROR [7f2b1f8ae700] (receiverd) Traceback (most recent call last):
  File "/usr/lib/python2.6/site-packages/nailgun/rpc/receiverd.py", line 52, in consume_msg
    callback(**body["args"])
  File "/usr/lib/python2.6/site-packages/nailgun/rpc/receiver.py", line 90, in remove_nodes_resp
    objects.NodeCollection.lock_for_update(locked_nodes).all()
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 2300, in all
    return list(self)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 2412, in __iter__
    return self._execute_and_instances(context)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 2427, in _execute_and_instances
    result = conn.execute(querycontext.statement, self._params)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/base.py", line 729, in execute
    return meth(self, multiparams, params)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/sql/elements.py", line 321, in _execute_on_connection
    return connection._execute_clauseelement(self, multiparams, params)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/base.py", line 826, in _execute_clauseelement
    compiled_sql, distilled_params
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/base.py", line 958, in _execute_context
    context)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/base.py", line 1160, in _handle_dbapi_exception
    exc_info
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/util/compat.py", line 199, in raise_from_cause
    reraise(type(exception), exception, tb=exc_tb)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/base.py", line 951, in _execute_context
    context)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/default.py", line 436, in do_execute
    cursor.execute(statement, parameters)
DBAPIError: (TransactionRollbackError) deadlock detected