Testing: port_behind_port: Ensure ports are of same network
Testing: port_behind_port: Ensure ports are of same network

If the ports are not of the same network, then there's a danger there
will be IP collision, and then the heuristic fails. So while not
necessary for the feature to work, it helps stability.

The scenario here both ports have the same IP is not relevant for
port-behind-port, and by definition cannot be used with ipvlan.

Change-Id: Ic0f365351ac44a962469cecb85f1640c7bf27668

openstack/dragonflow,openstack/dragonflow,openstack/dragonflow