在Symfony2中销毁给定的会话

Question

I'm working on a Symfony2 implementation of this http://php.net/manual/fr/function.session-destroy.php#114709

It's a function that destroys a session by its ID.

private function destroyGivenSessions($ssid)
{   

    $ssid = '1pfj5rj73knh2mdo8ks9iqng51'; // for tests

    $request = $this->getRequest();
    $session = $request->getSession();

    $currentSession = $session->getId(); // store current session

    $session->setId($ssid);
    $session->start();
    $session->invalidate();

    $session->setId($currentSession); // restore old session
    $session->start();
}

This function destroys the given session but, instead of restoring the old session stored in $currentSession, it regenerates a new ID so I end up destroying the given session and loosing my current session.. What am I doing wrong ?