Comment 9 for bug 1808171

So, what I think is fact that when port is initially added by os-vif, it triggers OvsdbMonitor event: http://logs.openstack.org/32/602432/3/check/tempest-full/4b76af0/controller/logs/screen-q-agt.txt.gz#_Jan_16_21_35_54_776433 and such port is added to events['added'] list thus neutron-openvswitch-agent process this port.
That is causing issues and some errors in logs as port is actually not configured yet (ofport=-1) so it isn't actually processed. But for some reason it's indeed added to port_info["current"] and if it happens, such port will be not processed later probably as it already is in "current" list.

I think that we should skip events for ports with ofport=-1, there is no need to trigger ovs agent when such port is added to bridge IMO.