Issue #2582475 by alexpott: Installation fails if a valid config sync directory is defined

core/includes/install.core.inc

@@ -7,7 +7,6 @@
 
 use Drupal\Component\Utility\UrlHelper;
 use Drupal\Core\DrupalKernel;
-use Drupal\Core\Config\BootstrapConfigStorageFactory;
 use Drupal\Core\Database\Database;
 use Drupal\Core\Database\DatabaseExceptionWrapper;
 use Drupal\Core\Form\FormState;
@@ -489,8 +488,7 @@ function install_begin_request($class_loader, &$install_state) {
 
   // Ensure that the active configuration is empty before installation starts.
   if ($install_state['config_verified'] && empty($task)) {
-    $config = BootstrapConfigStorageFactory::get()->listAll();
-    if (!empty($config)) {
+    if (count($kernel->getConfigStorage()->listAll())) {
       $task = NULL;
       throw new AlreadyInstalledException($container->get('string_translation'));
     }

core/lib/Drupal/Core/Installer/InstallerKernel.php

@@ -33,4 +33,17 @@ public function resetConfigStorage() {
     $this->configStorage = NULL;
   }
 
+  /**
+   * Returns the active configuration storage used during early install.
+   *
+   * This override changes the visibility so that the installer can access
+   * config storage before the container is properly built.
+   *
+   * @return \Drupal\Core\Config\StorageInterface
+   *   The config storage.
+   */
+  public function getConfigStorage() {
+    return parent::getConfigStorage();
+  }
+
 }

core/modules/system/src/Tests/Installer/InstallerExistingConfigDirectoryTest.php

+<?php
+
+namespace Drupal\system\Tests\Installer;
+
+use Drupal\simpletest\InstallerTestBase;
+
+/**
+ * Tests the installer when a config_directory has already been set up.
+ *
+ * @group Installer
+ */
+class InstallerExistingConfigDirectoryTest extends InstallerTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    $this->settings['config_directories'][CONFIG_SYNC_DIRECTORY] = (object) array(
+      'value' => $this->siteDirectory . '/config',
+      'required' => TRUE,
+    );
+    parent::setUp();
+  }
+
+  /**
+   * Verifies that installation succeeded.
+   */
+  public function testInstaller() {
+    $this->assertUrl('user/1');
+    $this->assertResponse(200);
+  }
+
+}