/usr/share/debhelper/autoscripts/prerm-dzinstance is in zope-debhelper 0.3.15.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38  | PKG=#DZ-PKG#
INSTANCE=#DZ-INSTANCE#
ZVER=#DZ-ZVER#
DATABASE=#DZ-DATABASE#
[ -n "$(echo $INSTANCE)" ] || exit 1
if command -v invoke-rc.d >/dev/null 2>&1; then
	INVOKE="invoke-rc.d zope$ZVER"
else
	INVOKE="/etc/init.d/zope$ZVER"
fi
remove_products()
{
    products="#DZ-PRODUCTS#"
    if [ -n "$products" ]; then
	dzhandle -z $ZVER remove-product --lazy --force $INSTANCE $products
    fi
}
case "$1" in
  remove|upgrade)
    if [ "$DATABASE" = "ZEO" ]; then
	$INVOKE stop "ZEOSERVER=$INSTANCE" || true
    fi
    $INVOKE stop "INSTANCE=$INSTANCE" || true
    remove_products || true
    ;;
  failed-upgrade|deconfigure)
    ;;
  *)
    echo "prerm called with unknown argument \`$1'" >&2
    exit 1
    ;;
esac
 |