[FIX] stock: default quantity to return

The code was wrongly always taking the reserved quantity on the already
returned moves, but if they're done their value is zero.

task-2291973

closes odoo/odoo#54807

X-original-commit: 7b08f0ae0a39e8f575b21e744de16264b6365704
Signed-off-by: Simon Lejeune (sle) <sle@openerp.com>

addons/stock/wizard/stock_picking_return.py

@@ -77,11 +77,12 @@ class ReturnPicking(models.TransientModel):
 
     @api.model
     def _prepare_stock_return_picking_line_vals_from_move(self, stock_move):
-        quantity = stock_move.product_qty - sum(
-            stock_move.move_dest_ids
-            .filtered(lambda m: m.state in ['partially_available', 'assigned', 'done'])
-            .mapped('move_line_ids.product_qty')
-        )
+        quantity = stock_move.product_qty
+        for move in stock_move.move_dest_ids:
+            if move.state in ('partially_available', 'assigned'):
+                quantity -= sum(move.move_line_ids.mapped('product_qty'))
+            elif move.state in ('done'):
+                quantity -= move.product_qty
         quantity = float_round(quantity, precision_rounding=stock_move.product_uom.rounding)
         return {
             'product_id': stock_move.product_id.id,