"501 Not Implemented" but core/wget says redirect "302"

How are you testing HTTPRL module? I wish I would not find more issues... :-(((

function httprl_admin_settings_form() {

  $headers = array();
  $headers['User-Agent'] = 'User-Agent: Drupal (+http://drupal.org/)';

  // Add in the headers and enable blocking mode.
  $options = array(
    'blocking' => TRUE,
    'headers' => $headers,
    'method' => 'HEAD',
    'max_redirects' => 1,
  );

  $urls = array(
  	'http://www.bma.bund.de/index.cfm?8AC792DB077C4AB5BDB675A52577F0BE',
  );

  foreach ($urls as $url) {
    // Queue up the requests.
    httprl_request($url, $options);

    // Compare to core:
    krumo(drupal_http_request($url, $options));
  }

  // Execute requests.
  $responses = httprl_send_request();
  foreach ($responses as $response) {
    krumo($response);
  }