AppArmor: Prevents connection to system dbus (disconnected path)

[Felix Geyer]

AppArmor seems to prevent cupsd from connecting to the system dbus:

Sep 10 09:06:00 callisto kernel: audit: type=1400 audit(1410332760.203:112): apparmor="DENIED" operation="connect" info="Failed name lookup - disconnected path" error=-13 profile="/usr/sbin/cupsd" name="run/dbus/system_bus_socket" pid=3608 comm="cupsd" requested_mask="rw" denied_mask="rw" fsuid=0 ouid=0
Sep 10 09:06:31 callisto cupsd[3608]: process 3608: arguments to dbus_connection_unref() were incorrect, assertion "connection != NULL" failed in file ../../dbus/dbus-connection.c line 2794.
Sep 10 09:06:31 callisto cupsd[3608]: This is normally a bug in some application using the D-Bus library.

I got these errors since upgrading to utopic (Aug 22).
Might be worth noting that I'm using systemd as init.

Adding flags=(attach_disconnected) to the /usr/sbin/cupsd profile seems to fix this problem.