[FIX] account_invoice : origin field for refund invoice

When creating a Refund invoice, the field "origin" is fill with
the number of the invoice to refund

fix #5233
opw 627828

addons/account/account_invoice.py

@@ -1098,6 +1098,7 @@ class account_invoice(models.Model):
         values['date_invoice'] = date or fields.Date.context_today(invoice)
         values['state'] = 'draft'
         values['number'] = False
+        values['origin'] = invoice.number
 
         if period_id:
             values['period_id'] = period_id