py35: filter object isn't scriptable

The following is appearing in py35 jobs:

2017-01-19 17:01:30.705 25999 ERROR os_vif [req-1da0fa46-c1e7-4884-8b28-8834df89e0a1 tempest-AutoAllocateNetworkTest-1084110025 tempest-AutoAllocateNetworkTest-1084110025] Failed to plug vif VIFBridge(active=False,address=fa:16:3e:48:40:bb,bridge_name='brq9b67fef6-72',has_traffic_filtering=True,id=d43138d2-c515-4f02-9be4-1728acb5c3a8,network=Network(9b67fef6-7269-48be-bad0-9b5346d8c296),plugin='linux_bridge',port_profile=<?>,preserve_on_delete=False,vif_name='tapd43138d2-c5')
2017-01-19 17:01:30.705 25999 ERROR os_vif Traceback (most recent call last):
2017-01-19 17:01:30.705 25999 ERROR os_vif File "/usr/local/lib/python3.5/dist-packages/os_vif/__init__.py", line 80, in plug
2017-01-19 17:01:30.705 25999 ERROR os_vif plugin.plug(vif, instance_info)
2017-01-19 17:01:30.705 25999 ERROR os_vif File "/usr/local/lib/python3.5/dist-packages/vif_plug_linux_bridge/linux_bridge.py", line 105, in plug
2017-01-19 17:01:30.705 25999 ERROR os_vif linux_net.ensure_bridge(bridge_name, iface)
2017-01-19 17:01:30.705 25999 ERROR os_vif File "/usr/local/lib/python3.5/dist-packages/oslo_concurrency/lockutils.py", line 271, in inner
2017-01-19 17:01:30.705 25999 ERROR os_vif return f(*args, **kwargs)
2017-01-19 17:01:30.705 25999 ERROR os_vif File "/usr/local/lib/python3.5/dist-packages/vif_plug_linux_bridge/linux_net.py", line 103, in ensure_bridge
2017-01-19 17:01:30.705 25999 ERROR os_vif _ensure_bridge_filtering(bridge, gateway)
2017-01-19 17:01:30.705 25999 ERROR os_vif File "/usr/local/lib/python3.5/dist-packages/vif_plug_linux_bridge/linux_net.py", line 208, in _ensure_bridge_filtering
2017-01-19 17:01:30.705 25999 ERROR os_vif _IPTABLES_MANAGER.apply()
2017-01-19 17:01:30.705 25999 ERROR os_vif File "/usr/local/lib/python3.5/dist-packages/vif_plug_linux_bridge/iptables.py", line 349, in apply
2017-01-19 17:01:30.705 25999 ERROR os_vif self._apply()
2017-01-19 17:01:30.705 25999 ERROR os_vif File "/usr/local/lib/python3.5/dist-packages/oslo_concurrency/lockutils.py", line 271, in inner
2017-01-19 17:01:30.705 25999 ERROR os_vif return f(*args, **kwargs)
2017-01-19 17:01:30.705 25999 ERROR os_vif File "/usr/local/lib/python3.5/dist-packages/vif_plug_linux_bridge/iptables.py", line 370, in _apply
2017-01-19 17:01:30.705 25999 ERROR os_vif all_lines[start:end], table, table_name)
2017-01-19 17:01:30.705 25999 ERROR os_vif File "/usr/local/lib/python3.5/dist-packages/vif_plug_linux_bridge/iptables.py", line 461, in _modify_rules
2017-01-19 17:01:30.705 25999 ERROR os_vif dup = dup_filter[-1]
2017-01-19 17:01:30.705 25999 ERROR os_vif TypeError: 'filter' object is not subscriptable