Reproduced again on fuel 7.0 (kilo), caused BVT failure:

<163>Jul 30 14:07:58 node-4 neutron-server 2015-07-30 14:07:58.147 20498 ERROR oslo_db.api [req-2eeaf233-afa4-4a41-9661-a4b169a67afc ] DB error.
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api Traceback (most recent call last):
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/oslo_db/api.py", line 131, in wrapper
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     return f(*args, **kwargs)
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/neutron/plugins/ml2/plugin.py", line 1284, in delete_port
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     context, id, do_notify=False)
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/neutron/db/l3_dvr_db.py", line 267, in disassociate_floatingips
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     context, port_id=port_id)
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/neutron/db/l3_dvr_db.py", line 261, in _get_floatingip_on_port
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     return floating_ip.first()
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2341, in first
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     ret = list(self[0:1])
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2208, in __getitem__
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     return list(res)
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2412, in __iter__
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     return self._execute_and_instances(context)
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2427, in _execute_and_instances
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     result = conn.execute(querycontext.statement, self._params)
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 729, in execute
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     return meth(self, multiparams, params)
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/sqlalchemy/sql/elements.py", line 321, in _execute_on_connection
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     return connection._execute_clauseelement(self, multiparams, params)
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 826, in _execute_clauseelement
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     compiled_sql, distilled_params
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 958, in _execute_context
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     context)
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/oslo_db/sqlalchemy/compat/handle_error.py", line 261, in _handle_dbapi_exception
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     e, statement, parameters, cursor, context)
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1156, in _handle_dbapi_exception
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     util.raise_from_cause(newraise, exc_info)
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/sqlalchemy/util/compat.py", line 199, in raise_from_cause
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     reraise(type(exception), exception, tb=exc_tb)
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 951, in _execute_context
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     context)
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/default.py", line 436, in do_execute
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     cursor.execute(statement, parameters)
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/MySQLdb/cursors.py", line 205, in execute
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     self.errorhandler(self, exc, value)
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api   File "/usr/lib/python2.7/dist-packages/MySQLdb/connections.py", line 36, in defaulterrorhandler
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api     raise errorclass, errorvalue
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api DBDeadlock: (OperationalError) (1213, 'Deadlock found when trying to get lock; try restarting transaction') 'SELECT floatingip
d, floatingips.id AS floatingips_id, floatingips.floating_ip_address AS floatingips_floating_ip_address, floatingips.floating_network_id AS floatingips_floating_network_id, f
tingips_floating_port_id, floatingips.fixed_port_id AS floatingips_fixed_port_id, floatingips.fixed_ip_address AS floatingips_fixed_ip_address, floatingips.router_id AS float
known_router_id AS floatingips_last_known_router_id, floatingips.status AS floatingips_status \nFROM floatingips \nWHERE floatingips.fixed_port_id = %s \n LIMIT %s' ('5660211
2015-07-30 14:07:58.147 20498 TRACE oslo_db.api 

Fuel version info: http://paste.openstack.org/show/406449/