Comment 2 for bug 173143

Wasn't this fixed by this commit?

  * Deregister old debconf questions before calling dexconf. dexconf calls
     db_stop, and we can't use debconf after that. Add a comment to that
     effect above the dexconf call in debian/xserver-xorg.postinst.in, to try
     to prevent future mistakes. Thanks, Michael Vogt!