[FIX] stock: reserved quantity on return of return

1. Activate receipt in 2 steps
2. Make a PO of 10
3. Receive 8 (pick 1), backorder
4. Receive 2 (pick 2)
5. Unreserve the internal transfer (pick 3)
6. Go to pick 2, return 2 (pick 4)
   => product is sent back to the supplier
7. Go to pick 4, return 2 (pick 5)
   => product is received from the supplier
8. Go to pick 3, check availability

Only 8 units are reserved instead of 10.

It happens because pick 5 (return of the return) is not linked to the
pick 3 (internal transfer).

We use a similar approach for `move_dest_to_link` than the one used for
`move_orig_to_link`.

Closes #52459

opw-2271838

closes odoo/odoo#53506

X-original-commit: c96339dd94ffe1e9c5103814062455c79d93a273
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>

addons/stock/wizard/stock_picking_return.py

@@ -149,6 +149,14 @@ class ReturnPicking(models.TransientModel):
                     .mapped('move_dest_ids').filtered(lambda m: m.state not in ('cancel'))\
                     .mapped('move_orig_ids').filtered(lambda m: m.state not in ('cancel'))
                 move_dest_to_link = return_line.move_id.move_orig_ids.mapped('returned_move_ids')
+                # link to children of originally returned moves, if any. Note that the use of
+                # 'return_line.move_id.move_orig_ids.returned_move_ids.move_orig_ids.move_dest_ids'
+                # instead of 'return_line.move_id.move_orig_ids.move_dest_ids' prevents linking a
+                # return directly to the destination moves of its parents. However, the return of
+                # the return will be linked to the destination moves.
+                move_dest_to_link |= return_line.move_id.move_orig_ids.mapped('returned_move_ids')\
+                    .mapped('move_orig_ids').filtered(lambda m: m.state not in ('cancel'))\
+                    .mapped('move_dest_ids').filtered(lambda m: m.state not in ('cancel'))
                 vals['move_orig_ids'] = [(4, m.id) for m in move_orig_to_link]
                 vals['move_dest_ids'] = [(4, m.id) for m in move_dest_to_link]
                 r.write(vals)