http://logs.openstack.org/51/232451/11/experimental/gate-install-dsvm-networking-bgpvpn-bagpipe-liberty/25b1428/logs/screen-q-svc.txt.gz#_2015-12-16_09_16_49_415
2015-12-16 09:16:49.415 1866 ERROR networking_bgpvpn.neutron.services.service_drivers.bagpipe.bagpipe Traceback (most recent call last):
2015-12-16 09:16:49.415 1866 ERROR networking_bgpvpn.neutron.services.service_drivers.bagpipe.bagpipe File "/opt/stack/new/networking-bgpvpn/networking_bgpvpn/neutron/services/service_drivers/bagpipe/bagpipe.py", line 456, in registry_port_updated
2015-12-16 09:16:49.415 1866 ERROR networking_bgpvpn.neutron.services.service_drivers.bagpipe.bagpipe self.notify_port_updated(context, port['id'])
2015-12-16 09:16:49.415 1866 ERROR networking_bgpvpn.neutron.services.service_drivers.bagpipe.bagpipe File "/opt/stack/new/networking-bgpvpn/networking_bgpvpn/neutron/services/service_drivers/bagpipe/bagpipe.py", line 355, in notify_port_updated
2015-12-16 09:16:49.415 1866 ERROR networking_bgpvpn.neutron.services.service_drivers.bagpipe.bagpipe self._retrieve_bgpvpn_network_info_for_port(context, port)
2015-12-16 09:16:49.415 1866 ERROR networking_bgpvpn.neutron.services.service_drivers.bagpipe.bagpipe File "/opt/stack/new/networking-bgpvpn/networking_bgpvpn/neutron/services/service_drivers/bagpipe/bagpipe.py", line 263, in _retrieve_bgpvpn_network_info_for_port
2015-12-16 09:16:49.415 1866 ERROR networking_bgpvpn.neutron.services.service_drivers.bagpipe.bagpipe network_info = get_network_info_for_port(context, port_id)
2015-12-16 09:16:49.415 1866 ERROR networking_bgpvpn.neutron.services.service_drivers.bagpipe.bagpipe File "/opt/stack/new/networking-bgpvpn/networking_bgpvpn/neutron/services/service_drivers/bagpipe/bagpipe.py", line 57, in get_network_info_for_port
2015-12-16 09:16:49.415 1866 ERROR networking_bgpvpn.neutron.services.service_drivers.bagpipe.bagpipe filter(models_v2.Port.id == port_id).one())
2015-12-16 09:16:49.415 1866 ERROR networking_bgpvpn.neutron.services.service_drivers.bagpipe.bagpipe File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2698, in one
2015-12-16 09:16:49.415 1866 ERROR networking_bgpvpn.neutron.services.service_drivers.bagpipe.bagpipe "Multiple rows were found for one()")
2015-12-16 09:16:49.415 1866 ERROR networking_bgpvpn.neutron.services.service_drivers.bagpipe.bagpipe MultipleResultsFound: Multiple rows were found for one()
The issue happens after adding an IPv6 subnet, so I suspect that the query returns multiple gateways, one for IPv4 and one for IPv6.
If this assumption is correct, then the solution would be to restrict the query to Subnets having ip_version == 4 (which makes a lot of sense anyways, until we support v6).