[FIX]stock:The Return Products wizard in Delivery Orders does not take into account the field Invoicing

lp bug: https://launchpad.net/bugs/1066127 fixed

bzr revid: mma@tinyerp.com-20121126111811-8o73t35m87wf8ce2

addons/stock/stock.py

@@ -712,7 +712,7 @@ class stock_picking(osv.osv):
             default['name'] = self.pool.get('ir.sequence').get(cr, uid, seq_obj_name)
             default['origin'] = ''
             default['backorder_id'] = False
-        if picking_obj.invoice_state == 'invoiced':
+        if 'invoice_state' not in default and picking_obj.invoice_state == 'invoiced':
             default['invoice_state'] = '2binvoiced'
         res=super(stock_picking, self).copy(cr, uid, id, default, context)
         if res: