only in patch2:
unchanged:
--- a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -719,11 +719,12 @@ abstract class WebTestBase extends TestBase {
       $this->assertTrue($success, t('Enabled modules: %modules', array('%modules' => implode(', ', $modules))));
     }
 
-    // Create a new DrupalKernel for testing purposes, now that all required
-    // modules have been enabled. This also stores a new dependency injection
-    // container in drupal_container(). Drupal\simpletest\TestBase::tearDown()
-    // restores the original container.
+    // Now that all required modules are enabled, reset drupal_container() and
+    // create a new DrupalKernel for testing purposes, which when booted, will
+    // store a new dependency injection container in drupal_container().
+    // Drupal\simpletest\TestBase::tearDown() restores the original container.
     // @see Drupal\Core\DrupalKernel::initializeContainer()
+    drupal_container(NULL, TRUE);
     $this->kernel = new DrupalKernel('testing', FALSE);
     // Booting the kernel is necessary to initialize the new DIC. While
     // normally the kernel gets booted on demand in