Sorry, but that doesn't work either:

bob$ sudo apt-get install --reinstall --purge emacsen-common
[sudo] password for bob: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libatk1.0-dev libxcb-shm0-dev libpango1.0-dev fp-units-gfx fp-utils fp-units-gtk libcairo2-dev
  libdts-dev fp-units-net fp-units-db libogg-dev fp-units-math fp-units-fv fp-units-misc dict
  libgtk2.0-dev recode libdca-dev libmad0-dev fp-ide liba52-0.7.4-dev libcairo-gobject2 libmaa2
  libmodplug0c2 libxcb-render0-dev fp-units-gnome1 libgdk-pixbuf2.0-dev libvorbis-dev
Use 'apt-get autoremove' to remove them.
0 upgraded, 0 newly installed, 1 reinstalled, 0 to remove and 1 not upgraded.
4 not fully installed or removed.
Need to get 0B/19.0kB of archives.
After this operation, 0B of additional disk space will be used.
(Reading database ... 266804 files and directories currently installed.)
Preparing to replace emacsen-common 1.4.19ubuntu1 (using .../emacsen-common_1.4.19ubuntu1_all.deb) ...
emacsen-common: Handling removal of emacsen flavor emacs
Unpacking replacement emacsen-common ...
Setting up emacs-snapshot (1:20090909-1) ...
Byte-compiling add-on packages, please wait... failed.

!! Byte-compilation for emacs-snapshot failed!
!! This indicates a bug in one of the add-on packages
!! installed on your system, or a bug in Emacs itself.
!! Please file a bug report against emacs-snapshot
!! and attach the file /tmp/emacs-snapshot.QBb35k
dpkg: error processing emacs-snapshot (--configure):
 subprocess installed post-installation script returned error exit status 1
dpkg: dependency problems prevent configuration of emacs-snapshot-gtk:
 emacs-snapshot-gtk depends on emacs-snapshot; however:
  Package emacs-snapshot is not configured yet.
dpkg: error processing emacs-snapshot-gtk (--configure):
 dependency problems - leaving unconfigured
Setting up emacs23-lucid (23.1+1-4ubuntu7) ...
No apport report written because the error message indicates its a followup error from a previous failure.
      emacs-install emacs23
install/a2ps: Handling install for emacsen flavor emacs23
Warning: Lisp directory `/usr/local/share/emacs/site-lisp' does not exist.
Wrote /usr/share/emacs23/site-lisp/a2ps/path.elc
install/auctex: Setting up for emacs23 (log file: /usr/share/emacs23/site-lisp/auctex//CompilationLog)... done.
update-auctex-elisp[25067]: Further output will appear in: /var/log/auctex-emacs23.log.
install/dictionaries-common: Already byte-compiled for emacs23. Skipping ...
emacsen-common: Handling install of emacsen flavor emacs23
emacsen-common: byte-compiling for emacs23
cp: cannot stat `/etc/emacs/site-start.d/00debian-vars.el': No such file or directory
emacs-install: /usr/lib/emacsen-common/packages/install/emacsen-common emacs23 failed at /usr/lib/emacsen-common/emacs-install line 28, <TSORT> line 4.
dpkg: error processing emacs23-lucid (--configure):
 subprocess installed post-installation script returned error exit status 1
dpkg: dependency problems prevent configuration of auctex:
 auctex depends on emacs23 | emacs22 | emacs21 | emacs-snapshot; however:
  Package emacs23 is not installed.
  Package emacs23-lucid which provides emacs23 is not configured yet.
  Package emacs22 is not installed.
  Package emacs21 is not installed.
  Package emacs-snapshot is not configured yet.
dpkg: error processing auctex (--configure):
 dependency problems - leaving unconfigured
Setting up emacsen-common (1.4.19ubuntu1) ...
No apport report written because MaxReports is reached already
                                                              emacsen-common: Handling install of emacsen flavor emacs
Errors were encountered while processing:
 emacs-snapshot
 emacs-snapshot-gtk
 emacs23-lucid
 auctex
E: Sub-process /usr/bin/dpkg returned an error code (1)


And the log file:

bob$ sudo cat /tmp/emacs-snapshot.QBb35k
emacs-install emacs-snapshot
install/a2ps: Handling install for emacsen flavor emacs-snapshot
Warning: Lisp directory `/usr/local/share/emacs/site-lisp' does not exist.
Wrote /usr/share/emacs-snapshot/site-lisp/a2ps/path.elc
install/auctex: Setting up for emacs-snapshot (log file: /usr/share/emacs-snapshot/site-lisp/auctex//CompilationLog)... done.
update-auctex-elisp[23739]: Further output will appear in: /var/log/auctex-emacs-snapshot.log.
install/dictionaries-common: Skipping byte-compilation for emacs-snapshot
emacsen-common: Handling install of emacsen flavor emacs-snapshot
emacsen-common: byte-compiling for emacs-snapshot
cp: cannot stat `/etc/emacs/site-start.d/00debian-vars.el': No such file or directory
emacs-install: /usr/lib/emacsen-common/packages/install/emacsen-common emacs-snapshot failed at /usr/lib/emacsen-common/emacs-install line 28, <TSORT> line 4.

Hope someone can figure this out. Funny thing, emacs does work on this interupted install. Most annoying is that any other installs of any other packages forces another try to install emacs ... and yet another error.