pubsub identity bug

gistfile1.txt

<?php
$context = new ZMQContext();
$pub = $context->getSocket(ZMQ::SOCKET_PUB);
$pub->bind('tcp://*:5566');
$sub = makesock($context);
$sub2 = makesock($context);

$pub->send(rand(0,10));

function makesock($context) {
    $sub = $context->getSocket(ZMQ::SOCKET_SUB);
    $sub->setSockOpt(ZMQ::SOCKOPT_SUBSCRIBE, "");
    $sub->setSockOpt(ZMQ::SOCKOPT_IDENTITY, "test");
    $sub->connect('tcp://localhost:5566');
    return $sub;
}