Comment # 3 on bug 984329 from Christian Boltz

You need to add the attach_disconnected flag.

Edit /etc/apparmor.d/usr.sbin.avahi-daemon and replace
    /usr/sbin/avahi-daemon {
with
    /usr/sbin/avahi-daemon flags=(attach_disconnected) {

Then run "rcapparmor reload" to reload the profiles.