Datapath_id potentially changes as ports are added to bridge

OVS sets the datapath_id using the following algorithm:

if other_config:datapath_id is specified
use that
otherwise if other_config:hwaddr specified
use that
otherwise if this bridge has ports
use the lowest mac address of the ports on this bridge
otherwise
use a randomly generated mac

this algorithm is re-run every time you add or remove a port from the bridge. So, if a port is added with a lower mac, the dpid will change mid-flight. As you can imagine this should really screw up the state, especially WRT operational vs. configuration. During tests it was observed that when this occurs flows are not properly installed in OVS.