Bruce Perens writes ("Bug#3149: upgrading base truncates utmp"):
...
> > What is /tmp/base.postinst for?
>
> The base disk creation script runs it. I think it may not be a security
> problem because dpkg moves it out of the way before replacing it.
> There may be a small race window there.
Err, umm, wibble - does it really need to be in /tmp ?
Ian.