Bug#605717: !-based escape to shell for cdebconf text UI

[Ian Jackson <Ian.Jackson@eu.citrix.com>]

Package: cdebconf
Severity: wishlist

It would be nice if at a cdebconf text prompt, you could say ! to get
a subshell.  This is particularly important in debian-installer; there
are situations where things have gone wrong and you get into loops in
the installer.

If you're on a serial (or Xen PV) console you don't have the shell on
tty2 available so you're basically stuck.

(Sorry for not including a version tag; I'm talking about the version
included in lenny's installer.)

Thanks,
Ian.