内存泄漏：PHP guzzle / oauth-subscriber

When using oauth-subscriber in cron for multiple times their is a memory leak. Here is a basic test I did.

function oauth_1_stack($token = NULL, $token_secret = NULL)
{
    $stack = HandlerStack::create();

    $middleware = new Oauth1([
        'consumer_key'    => 'consumer_key',
        'consumer_secret' => 'consumer_secret',
        'token'           => $token,
        'token_secret'    => $token_secret,
    ]);
    $stack->push($middleware);

    $options = [
      'handler' => $stack,
      'auth' => 'oauth'
    ];

    unset($stack, $middleware);

    return $options;
}

echo memory_get_usage() . "
"; // 4017480

$options = oauth_1_stack();

echo memory_get_usage() . "
"; // 4509824

unset($options);

echo memory_get_usage() . "
"; // 4480032

GitHub issue I logged: https://github.com/guzzle/oauth-subscriber/issues/47

So can I do something to counterfeit this leak?