diff -u b/core/lib/Drupal/Core/DrupalKernel.php b/core/lib/Drupal/Core/DrupalKernel.php
--- b/core/lib/Drupal/Core/DrupalKernel.php
+++ b/core/lib/Drupal/Core/DrupalKernel.php
@@ -169,6 +169,12 @@
     }
   }
 
+  /**
+   * Returns the classname based on environment, debug and testing prefix.
+   *
+   * @return string
+   *   The class name.
+   */
   protected function getClassName() {
     $parts = array('service_container', $this->environment, $this->debug);
     if (!empty($GLOBALS['drupal_test_info']['test_run_id'])) {
reverted:
--- b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
+++ a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
@@ -890,7 +890,6 @@
     $test_info = &$GLOBALS['drupal_test_info'];
     $test_info['test_run_id'] = $this->databasePrefix;
     $test_info['in_child_site'] = FALSE;
-    $test_info['config_directory_active'] = $this->originalConfigDirectories['active'];
 
     // Indicate the environment was set up correctly.
     $this->setupEnvironment = TRUE;
reverted:
--- b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -713,17 +713,7 @@
     // Reset the static batch to remove Simpletest's batch operations.
     $batch = &batch_get();
     $batch = array();
+
-    $file_variables = array(
-      'file_public_path' => $this->public_files_directory,
-      'file_private_path' => $this->private_files_directory,
-      'file_temporary_path' => $this->temp_files_directory,
-      'locale_translate_file_directory' => $this->translation_files_directory,
-    );
-    // Make sure the installer writes to the proper directories.
-    foreach ($file_variables as $name => $value) {
-      $GLOBALS['conf'][$name] = $value;
-    }
-    drupal_static_reset('drupal_php_storage');
     // Execute the non-interactive installer.
     require_once DRUPAL_ROOT . '/core/includes/install.core.inc';
     install_drupal($settings);
@@ -737,10 +727,12 @@
     unset($conf['cache_classes']);
     unset($conf['lock_backend']);
 
+    // Set path variables.
+    variable_set('file_public_path', $this->public_files_directory);
+    variable_set('file_private_path', $this->private_files_directory);
+    variable_set('file_temporary_path', $this->temp_files_directory);
+    variable_set('locale_translate_file_directory', $this->translation_files_directory);
+
-    // Persist path variables.
-    foreach ($file_variables as $name => $value) {
-      variable_set($name, $value);
-    }
     // Set 'parent_profile' of simpletest to add the parent profile's
     // search path to the child site's search paths.
     // @see drupal_system_listing()