That's when you use Apache::compat, doing the mp1 syntax. In mp2-speak that would be:
$r->err_headers_out->add('Set-Cookie' => $packed_cookie); $r->headers_out->set('Location' => $url); $r->status(REDIRECT);
notice that you don't need to call $r->send_http_header, it doesn't exist in mp2.
not to mention it's entirely unnecessary (and undesirable) to send headers on error responses such as redirects.
and you should never set $r->status from a handler - for Registry scripts it's ok, since we use it as a hack to get around some things, but handlers should never manipulate the value of $r->status.
--Geoff