UnboundLocalError during ostf connectivity with of_interface=native

This is part of a lot more complicated problem (arp storm with native of_interface).
Keep in mind that it is not the default deployment of neutron-openvswitch-agent.

Env:
Mos 9.0, 3 controllers/1 compute.
Custom neutron configuration:
/etc/neutron/plugins/ml2/openvswitch_agent.ini has of_interface=native

Steps to reproduce:
restart OVS agent on all controllers and compute, run OSTF Connectivity test.

Result: ARP storm with the following in the logs (apart from hundreds of other errors)

2016-05-25 14:57:28 ERR ryu.lib.hub [req-6efe2697-b494-4c54-97dc-4d8d1f43cab6 - - - - -] hub: uncaught exception: Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/ryu/lib/hub.py", line 52, in _launch
    func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/neutron/plugins/ml2/drivers/openvswitch/agent/openflow/native/ovs_ryuapp.py", line 35, in agent_main_wrapper
    ovs_agent.main(bridge_classes)
  File "/usr/lib/python2.7/dist-packages/neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py", line 2118, in main
    agent.daemon_loop()
  File "/usr/lib/python2.7/dist-packages/neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py", line 2041, in daemon_loop
    self.rpc_loop(polling_manager=pm)
  File "/usr/lib/python2.7/dist-packages/neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py", line 1910, in rpc_loop
    ovs_status = self.check_ovs_status()
  File "/usr/lib/python2.7/dist-packages/neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py", line 1718, in check_ovs_status
    status = self.int_br.check_canary_table()
  File "/usr/lib/python2.7/dist-packages/neutron/plugins/ml2/drivers/openvswitch/agent/openflow/native/br_int.py", line 52, in check_canary_table
    flows = self.dump_flows(constants.CANARY_TABLE)
  File "/usr/lib/python2.7/dist-packages/neutron/plugins/ml2/drivers/openvswitch/agent/openflow/native/ofswitch.py", line 125, in dump_flows
    (dp, ofp, ofpp) = self._get_dp()
  File "/usr/lib/python2.7/dist-packages/neutron/plugins/ml2/drivers/openvswitch/agent/openflow/native/ovs_bridge.py", line 61, in _get_dp
    if new_dpid_str != dpid_str:
UnboundLocalError: local variable 'dpid_str' referenced before assignment