[FIX] stock: update SO line (reserved package)

Steps to Reproduce:
- Activate packaging
- Create a storable product update on hand qty 1 package: "PACK6"
- Create a sale order with the product qty 1
- Confirm the order, picking will have a package already assigned
- Edit the sale order and set the product quantity to 0

Bug:
a new move will be created with negtaive quantity and merged with original
(correct behaviour)
but when the picking is confirmed an extra move will be created due to the
picking still having a package level set

Fix:
unlink the package level when its last linked SML is unlinked

opw-3597188

closes odoo/odoo#150939

X-original-commit: 4983923973bacbff84d67cdd442d4b6985f33577
Signed-off-by: William Henrotin (whe) <whe@odoo.com>
Signed-off-by: Walid Hanniche (waha) <waha@odoo.com>

addons/sale_stock/tests/test_sale_stock.py

@@ -1183,6 +1183,29 @@ class TestSaleStock(TestSaleCommon, ValuationReconciliationTestCommon):
 
         self.assertEqual(len(sale_order.picking_ids), 2)
 
+    def test_update_so_line_qty_with_package(self):
+        """
+        Creates a sale order, then validates the delivery
+        modifying the sale order lines qty to 0
+        move line should be deleted.
+        """
+        self.product_a.type = 'product'
+        self.env['stock.quant']._update_available_quantity(
+            self.product_a, self.company_data['default_warehouse'].lot_stock_id, 10,
+            package_id=self.env['stock.quant.package'].create({'name': 'PacMan'}))
+
+        # Create sale order
+        sale_order = self._get_new_sale_order(product=self.product_a)
+        sale_order.action_confirm()
+
+        # Update the SO line
+        with Form(sale_order.with_context(import_file=True)) as so_form:
+            with so_form.order_line.edit(0) as line:
+                line.product_uom_qty = 0
+
+        self.assertFalse(sale_order.picking_ids.package_level_ids)
+        self.assertFalse(sale_order.picking_ids.move_line_ids)
+
     def test_multiple_returns(self):
         # Creates a sale order for 10 products.
         sale_order = self._get_new_sale_order()

addons/stock/models/stock_move_line.py

@@ -488,7 +488,11 @@ class StockMoveLine(models.Model):
                 quants = quants_by_product[ml.product_id.id]
                 quants._update_reserved_quantity(ml.product_id, ml.location_id, -ml.quantity_product_uom, lot_id=ml.lot_id, package_id=ml.package_id, owner_id=ml.owner_id, strict=True)
         moves = self.mapped('move_id')
+        package_levels = self.package_level_id
         res = super().unlink()
+        package_levels = package_levels.filtered(lambda pl: not (pl.move_line_ids or pl.move_ids))
+        if package_levels:
+            package_levels.unlink()
         if moves:
             # Add with_prefetch() to set the _prefecht_ids = _ids
             # because _prefecht_ids generator look lazily on the cache of move_id