[RFC] AUFS disabled for 12.04

[Gary Poster]

Hi.

aufs was reliable for us on Oneiric when creating ephemeral lxc 
instances based on an underlying template.  The most recent overlayfs 
issue that we discovered is today's 
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/944386

The summary is that, within an overlayfs, this fails:

gary at garubtosh:~/tmp$ touch 3
gary at garubtosh:~/tmp$ chmod 0444 3
gary at garubtosh:~/tmp$ ln 3 4
ln: failed to create hard link `4' => `3': Operation not permitted

That error makes xvfb unable to start, in this particular case.

I'd feel a *lot* more comfortable if aufs were still around, in case we 
end up not finding the next overlayfs bug until it is too late for our 
project's delivery.

Thank you,

Gary