Comment 4 for bug 1054442

I've submitted this change to Debian, but it is going to be reverted because according to Section 6.5 of the Debian Policy (http://www.debian.org/doc/debian-policy/ch-maintainerscripts.html), prerm is called only as:

- prerm remove
- prerm upgrade […]
- prerm remove in-favour […]
- prerm deconfigure in-favour […]

It never gets called as `prerm purge`. I believe this is the case in Ubuntu as well, so I see no reason to keep this change in our delta.