Comment 14 for bug 1553617

Thanks Mike. In general we're going to run into some awkwardness if we
use mac addresses as a key. Mac addresses can move about. There's the
bonding thing, and I think quite a few things futz with mac addresses as
well, like macvlan's etc. And of course people can move network cards
around just for fun, too :) I don't have any off-the-cuff idea for a
better identifier of the hardware, but it bears thinking about.