[FIX] mrp: set default quantity

The wizard to change the produced quantity of a manufacturing order was not
using the current produced quantity as the default value.
This was because the field mo_id was not present in the view (and not in
`fields` in default_get).

Adding the field as invisible to compute the default value for mo_id.

Correct typo in dictory lookup (using `[` instead of `(`)

Closes #17937
opw-749725

addons/mrp/wizard/change_production_qty.py

@@ -22,7 +22,7 @@ class ChangeProductionQty(models.TransientModel):
         if 'mo_id' in fields and not res.get('mo_id') and self._context.get('active_model') == 'mrp.production' and self._context.get('active_id'):
             res['mo_id'] = self._context['active_id']
         if 'product_qty' in fields and not res.get('product_qty') and res.get('mo_id'):
-            res['product_qty'] = self.env['mrp.production'].browse(res.get['mo_id']).product_qty
+            res['product_qty'] = self.env['mrp.production'].browse(res['mo_id']).product_qty
         return res
 
     @api.model

addons/mrp/wizard/change_production_qty_views.xml

@@ -10,6 +10,7 @@
                 <form string="Change Product Qty">
                     <group>
                         <field name="product_qty"/>
+                        <field name="mo_id" invisible="1"/>
                     </group>
                     <footer>
                         <button name="change_prod_qty" string="Approve"