The initial start of the neutron OVS agent always prints
a warning:
WARNING stevedore.named [] Could not load
neutron.agent.linux.iptables_firewall.OVSHybridIptablesFirewallDriver
There's an alias for that in setup.cfg called
iptables_hybrid that would avoid it.
Change-Id: I3f5bf782f4f27dc123e462e494741a8a941641ec