[IMP] To determine the invoice we put extra moves in, it is better to…

… take the values from the sale order / purchase order if we can find it through the picking

[IMP] Add comments

[IMP] Simplify code

addons/purchase/stock.py

@@ -89,7 +89,13 @@ def _get_master_data(self, cr, uid, move, company, context=None):
         if move.purchase_line_id:
             purchase_order = move.purchase_line_id.order_id
             return purchase_order.partner_id, purchase_order.create_uid.id, purchase_order.currency_id.id
-        else:
+        elif move.picking_id:
+            # In case of an extra move, it is better to use the data from the original moves
+            for purchase_move in move.picking_id.move_lines:
+                if purchase_move.purchase_line_id:
+                    purchase_order = purchase_move.purchase_line_id.order_id
+                    return purchase_order.partner_id, purchase_order.create_uid.id, purchase_order.currency_id.id
+
             partner = move.picking_id and move.picking_id.partner_id or False
             code = self.get_code_from_locs(cr, uid, move, context=context)
             if partner and partner.property_product_pricelist_purchase and code == 'incoming':

addons/sale_stock/sale_stock.py

@@ -381,6 +381,10 @@ def _get_master_data(self, cr, uid, move, company, context=None):
         if move.procurement_id and move.procurement_id.sale_line_id and move.procurement_id.sale_line_id.order_id.order_policy == 'picking':
             sale_order = move.procurement_id.sale_line_id.order_id
             return sale_order.partner_invoice_id, sale_order.user_id.id, sale_order.pricelist_id.currency_id.id
+        elif move.picking_id.sale_id:
+            # In case of extra move, it is better to use the same data as the original moves
+            sale_order = move.picking_id.sale_id
+            return sale_order.partner_invoice_id, sale_order.user_id.id, sale_order.pricelist_id.currency_id.id
         return super(stock_move, self)._get_master_data(cr, uid, move, company, context=context)
 
     def _get_invoice_line_vals(self, cr, uid, move, partner, inv_type, context=None):