pre_upgrade() {
  if(test `vercmp '3.4.3-5' "$2"` -ge 0); then
    mv /usr/share/jnethack /tmp/jnethack-backup
  fi
}

post_upgrade() {
  if(test `vercmp '3.4.3-5' "$2"` -ge 0); then
    rm -rf /var/games/jnethack
    mv /tmp/jnethack-backup /var/games/jnethack
  fi
}