I would like to append a header to a 'winning' negative reply in failure_route and let the Kamailio do the default action (state fully forward the winning reply).

When I use append_to_reply("Foo: bar\r\n"); and then call exit; in failure_route nothing is appended.
When I use same append_to_reply then t_relay("505","Error"); and exit; the header is appended.
When I use append and t_reply with dialog modul turned on I got a bug I'm solving here '[SR-Users] t_reply in failure route with dialog module'.

So my question is how to put a header into a reply when I don't want to alter its code or text?

I'm using Kamilio 4.0.4 on Debian 7.1

Thanks for an answer