[IMP] sale_stock: Check package qty in sale.order.line product_uom_qty onchange

On sale.order.line, the onchange on product_packaging ensures that a warning
is raised when changing the package if the qty on the line is not a multiple
of the package qty.
With this commit, a same warning is raised when changing the qty if the qty
on the line is not a multiple of the package qty.

closes odoo/odoo#78405

X-original-commit: ee9ea35a
Signed-off-by: William Henrotin (whe) <whe@odoo.com>

addons/sale_stock/models/sale_order.py

@@ -496,6 +496,8 @@ class SaleOrderLine(models.Model):
                 'message' : _('You are decreasing the ordered quantity! Do not forget to manually update the delivery order if needed.'),
             }
             return {'warning': warning_mess}
+        if self.product_packaging:
+            return self._check_package()
         return {}
 
     def _prepare_procurement_values(self, group_id=False):