OVSvApp agent throws exception during VM deletion

2015-09-07 02:47:32.730 DEBUG neutron.agent.linux.utils [-] Running command (rootwrap daemon): ['ovs-ofctl', 'dump-flows', 'br-int', 'table=23'] from (pid=25202) execute_rootwrap_daemon /opt/stack/neutron/neutron/agent/linux/utils.py:102
2015-09-07 02:47:32.743 DEBUG neutron.agent.linux.utils [-]
Command: ['ovs-ofctl', 'dump-flows', 'br-int', 'table=23']
Exit code: 0
 from (pid=25202) execute /opt/stack/neutron/neutron/agent/linux/utils.py:157
2015-09-07 02:47:33.031 DEBUG neutron.api.rpc.handlers.securitygroups_rpc [req-d2f9b498-28f6-4d14-9e98-1ce38f69785f admin 053e40ea830c498a836f46ad1b245d73] Security group member updated on remote: [u'a3ed90b9-79e9-407a-9af4-5e9379ba57f3'] from (pid=25202) security_groups_member_updated /opt/stack/neutron/neutron/api/rpc/handlers/securitygroups_rpc.py:202
2015-09-07 02:47:33.033 INFO neutron.agent.securitygroups_rpc [req-d2f9b498-28f6-4d14-9e98-1ce38f69785f admin 053e40ea830c498a836f46ad1b245d73] Security group member updated [u'a3ed90b9-79e9-407a-9af4-5e9379ba57f3']
2015-09-07 02:47:33.034 ERROR oslo_messaging.rpc.dispatcher [req-d2f9b498-28f6-4d14-9e98-1ce38f69785f admin 053e40ea830c498a836f46ad1b245d73] Exception during message handling:
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher Traceback (most recent call last):
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher File "/usr/local/lib/python2.7/dist-packages/oslo_messaging/rpc/dispatcher.py", line 142, in _dispatch_and_reply
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher executor_callback))
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher File "/usr/local/lib/python2.7/dist-packages/oslo_messaging/rpc/dispatcher.py", line 186, in _dispatch
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher executor_callback)
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher File "/usr/local/lib/python2.7/dist-packages/oslo_messaging/rpc/dispatcher.py", line 129, in _do_dispatch
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher result = func(ctxt, **new_args)
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher File "/opt/stack/neutron/neutron/api/rpc/handlers/securitygroups_rpc.py", line 205, in security_groups_member_updated
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher self.sg_agent.security_groups_member_updated(security_groups)
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher File "/opt/stack/neutron/neutron/agent/securitygroups_rpc.py", line 192, in security_groups_member_updated
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher 'sg_member')
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher File "/opt/stack/neutron/neutron/agent/securitygroups_rpc.py", line 201, in _security_group_updated
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher self.firewall.security_group_updated(action_type, sec_grp_set)
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher File "/opt/stack/neutron/neutron/agent/firewall.py", line 123, in security_group_updated
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher raise NotImplementedError()
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher NotImplementedError
2015-09-07 02:47:33.034 TRACE oslo_messaging.rpc.dispatcher