File: //var/lib/dpkg/info/qmail.preinst
#!/bin/sh
set -e
errcho() {
  echo "$*" >&2
}
if test "$1" = upgrade && dpkg --compare-versions "$2" lt 1.06; then
  case "$2" in
  *zarge*)
    if test -x /usr/lib/qmail/prepare-upgrade-from-unofficial; then
      /usr/lib/qmail/prepare-upgrade-from-unofficial
    else
      errcho "Upgrading from qmail version $2 is not yet supported."
      exit 1
    fi
    ;;
  *)
    if test -x /usr/lib/qmail/prepare-upgrade-from-nonfree; then
      /var/usr/qmail/prepare-upgrade-from-nonfree
    else
      errcho "Upgrading from qmail version $2 is not yet supported."
      exit 1
    fi
    ;;
  esac
fi