http\Client::dequeue() within http\Client::setDebug() causes segfault about ext-http HOT 8 CLOSED

<?php
class HTTPTransferObserver implements SplObserver {

        public function update(SplSubject $client, http\Client\Request $request = null, stdclass $progress = null)
        {
                return;
        }

        public function cancelRequest(http\Client $client, http\Client\Request $request, int $type, string $data)
        {
                if ($type & http\Client::DEBUG_HEADER) {
                        $client->reset();
                }
        }
}

$c = new http\Client;

$c->enqueue($request = new http\Client\Request("GET", "https://m6w6.name"));

$observer = new HTTPTransferObserver($request);

$c->attach($observer);

$c->setDebug(function(http\Client $c, http\Client\Request $r, int $type, string $data) {
        foreach ($c->getObservers() as $observer) {
                $observer->cancelRequest($c, $r, $type, $data);
        }
});

$c->send();

$c = new http\Client;
$c->enqueue(new http\Client\Request("GET", "http://example.com"));

$c->setDebug(function($client, $request, $type, $data) use (&$dequeue) {
    if (!$type) {
        printf("D: %d <%s>\n", $type, $data);
        if (sscanf($data, "\tTrying %s...", $ip)) {
            printf("Blocking %s\n", $ip);
            $dequeue[] = $request;
        }
    }
});
while ($c->once()) {
    while ($dequeue) {
        $c->dequeue(array_shift($dequeue));
    }
    $c->wait();
}