[9.0][FIX] wizards need to specify partner.

rma_sale/wizards/rma_add_sale.py

@@ -60,6 +60,7 @@ class RmaAddSale(models.TransientModel):
                 raise ValidationError("Please define a warehouse with a "
                                       "default rma location.")
         data = {
+            'partner_id': self.partner_id.id,
             'sale_line_id': line.id,
             'product_id': line.product_id.id,
             'origin': line.order_id.name,