Comment 1 for bug 1295703

As near as I can tell, this Neutron commit [1] modified the flow building behavior to reject modifying flows with a priority set [2]. However, there was no UT added to detect this case. Further, the agent code is clearly modifying flows with a priority set [3]. Thus, this error is being triggered.

I have a patch which removes priority from flow modification in the agent and all unit tests, and also adds a negative UT case to make sure we catch this in the future.

[1] https://review.openstack.org/#/c/58533/
[2] https://github.com/openstack/neutron/blob/master/neutron/agent/linux/ovs_lib.py#L544
[3] https://github.com/openstack/neutron/blob/master/neutron/plugins/openvswitch/agent/ovs_neutron_agent.py#L373