[FIX] stock: edit reserved qty on SML

Suppose a product P with an available quantity equal to 1. Suppose a
user writes on an existing SML for that product and sets the reserved
quantity to 2. When writing on such a field, `StockMoveLine.write` tries
to reserve the same quantity on the quants. If it fails (which would be
the case here because there is only one P available), the reserved
quantity of the SML is reset to 0 (and so does the reserved quantity of
the quant).
https://github.com/odoo/odoo/blob/b8423ba218e0736593c3329d7438ca09112a735f/addons/stock/models/stock_move_line.py#L301-L313

However, there is an issue: the incorrect reserved quantity is still in
`vals`. As a result, later on in the method, this incorrect value is
written on the SML:
https://github.com/odoo/odoo/blob/b8423ba218e0736593c3329d7438ca09112a735f/addons/stock/models/stock_move_line.py#L362
This creates an inconsistency: a SML affirms that 2 x P are reserved
while the reserved quantity of the quant is 0. Moreover, when marking
the SML as done, it will lead to a "unreserve more than..." issue.

OPW-2936689

closes odoo/odoo#100858

X-original-commit: 2ea52bbcdbc2beaac916fa5f127ffc0ab2650708
Signed-off-by: Arnold Moyaux (arm) <arm@odoo.com>
Signed-off-by: Adrien Widart <awt@odoo.com>

addons/stock/models/stock_move_line.py

@@ -405,6 +405,8 @@ class StockMoveLine(models.Model):
                         new_reserved_uom_qty = ml.product_id.uom_id._compute_quantity(reserved_qty, ml.product_uom_id, rounding_method='HALF-UP')
                         moves_to_recompute_state |= ml.move_id
                         ml.with_context(bypass_reservation_update=True).reserved_uom_qty = new_reserved_uom_qty
+                        # we don't want to override the new reserved quantity
+                        vals.pop('reserved_uom_qty', None)
 
         # When editing a done move line, the reserved availability of a potential chained move is impacted. Take care of running again `_action_assign` on the concerned moves.
         if updates or 'qty_done' in vals:

addons/stock/tests/test_move.py

@@ -3470,6 +3470,32 @@ class StockMove(TransactionCase):
         self.assertEqual(len(self.gather_relevant(self.product_lot, self.stock_location, lot_id=lot1, strict=True)), 0.0)
         self.assertEqual(len(self.gather_relevant(self.product_lot, self.stock_location, lot_id=lot2, strict=True)), 0.0)
 
+    def test_edit_reserved_move_line_9(self):
+        """
+        When writing on the reserved quantity on the SML, a process tries to
+        reserve the quants with that new quantity. If it fails (for instance
+        because the written quantity is more than actually available), this
+        quantity should be reset to 0.
+        """
+        self.env['stock.quant']._update_available_quantity(self.product, self.stock_location, 1.0)
+
+        out_move = self.env['stock.move'].create({
+            'name': self.product.name,
+            'location_id': self.stock_location.id,
+            'location_dest_id': self.customer_location.id,
+            'product_id': self.product.id,
+            'product_uom_qty': 1,
+            'product_uom': self.product.uom_id.id,
+        })
+        out_move._action_confirm()
+        out_move._action_assign()
+
+        # try to manually assign more than available
+        out_move.move_line_ids.reserved_uom_qty = 2
+
+        self.assertTrue(out_move.move_line_ids)
+        self.assertEqual(out_move.move_line_ids.reserved_uom_qty, 0, "The reserved quantity should be cancelled")
+
     def test_edit_done_move_line_1(self):
         """ Test that editing a done stock move line linked to an untracked product correctly and
         directly adapts the transfer. In this case, we edit the sublocation where we take the