Ok here is what I've done :
(solution for developpers. Needs a php server.)
I've writen a PHP script that get the file through redirection (using cURL) and return it.
It's another kind of redirection, but it works well with ifttt.
<?PHP
//get url parameter
$url = $_GET['url'];
// send the right headers
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Transfer-Encoding: binary');
header('Connection: Keep-Alive');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Pragma: public');
header('Content-Length: ' . filesize($file));
header('Content-Disposition: attachment; filename="toDownload.torrent"');
//then download the new file using curl to follow redirection :
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_ENCODING, "gzip"); // Important
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($ch, CURLOPT_TIMEOUT, 50);
$st = curl_exec($ch);
curl_close($ch);
exit;
?>
Then I've used Yahoo pipes to modify the torrent RSS feed so each link becomes :
http:// [my.server.url]/thisscript.php?url=http:// the.redirect.url/324pfokT5
it makes ifttt believe its not a redirection and download the good file ! :)