Comment 2 for bug 1103022

As discussed on IRC: As this is an one-time upgrade fix for cleaning up after the currently wrong /lib/udev/rules.d/40-qemu-system.rules, I'd much rather like to see this as an one-time action in postinst (which is the standard way of doing such operations on upgrade) than this patch, which would confuse matters even more and also potentially breaks custom rules which change the permissions of /dev/kvm.