[FIX] sale: missing triggers on invoice_ids

As 'invoice_ids' on sale.order is a computed field, creating
a refund should invalidate this field as 'invoice_ids'
should contain invoices, refunds, ...
When using the refund wizard, the credit note will be linked
to the SO lines (see `_refund_cleanup_lines` override in sale).
Without the new trigger, invoice_ids will not be recomputed, and
executing 'sale_order.invoice_ids[1]' will not return the refund
account.invoice.
This commit fixes it.

addons/sale/models/sale.py

@@ -39,7 +39,7 @@ class SaleOrder(models.Model):
                 'amount_total': amount_untaxed + amount_tax,
             })
 
-    @api.depends('state', 'order_line.invoice_status')
+    @api.depends('state', 'order_line.invoice_status', 'order_line.invoice_lines')
     def _get_invoiced(self):
         """
         Compute the invoice status of a SO. Possible statuses: