Issue #2176151 by sun: Rebuild.php does not include /core/vendor/autoload.php.

core/includes/bootstrap.inc

@@ -574,7 +574,6 @@ function drupal_settings_initialize() {
   if (is_readable(DRUPAL_ROOT . '/' . $conf_path . '/settings.php')) {
     include_once DRUPAL_ROOT . '/' . $conf_path . '/settings.php';
   }
-  require_once __DIR__ . '../../lib/Drupal/Component/Utility/Settings.php';
 
   new Settings(isset($settings) ? $settings : array());
   $is_https = isset($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) == 'on';
@@ -1732,6 +1731,7 @@ function drupal_anonymous_user() {
  *
  * In order to bootstrap Drupal from another PHP script, you can use this code:
  * @code
+ *   require_once '/path/to/drupal/core/vendor/autoload.php';
  *   require_once '/path/to/drupal/core/includes/bootstrap.inc';
  *   drupal_bootstrap(DRUPAL_BOOTSTRAP_FULL);
  * @endcode

core/rebuild.php

@@ -15,8 +15,9 @@
 // Change the directory to the Drupal root.
 chdir('..');
 
-require_once dirname(__DIR__) . '/core/includes/bootstrap.inc';
-require_once dirname(__DIR__) . '/core/includes/utility.inc';
+require_once __DIR__ . '/vendor/autoload.php';
+require_once __DIR__ . '/includes/bootstrap.inc';
+require_once __DIR__ . '/includes/utility.inc';
 
 drupal_bootstrap(DRUPAL_BOOTSTRAP_CONFIGURATION);