Bug#813141: chroot upgrade from jessie to stretch disables predictable network interface names

[Riku Voipio]

reassign 813141 udev
thanks

# we enabled net.ifnames in 220-7 by default; don't change iface names in
# virtualized envs (where 75-persistent-net-generator.rules didn't work)

I think we need a more precise check for affected systems rather than the
lack of existance of /etc/udev/rules.d/70-persistent-net.rules. For example
machines without network adapters would get disabled ifnames. once a 
network
adapter is attached, they would get a legacy ifnames.

Like the virtio-net check below, it should probably be restricted to 
affected
network drivers.