diff -u b/core/modules/simpletest/lib/Drupal/simpletest/Tests/SimpleTestTest.php b/core/modules/simpletest/lib/Drupal/simpletest/Tests/SimpleTestTest.php
--- b/core/modules/simpletest/lib/Drupal/simpletest/Tests/SimpleTestTest.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/Tests/SimpleTestTest.php
@@ -71,8 +71,6 @@
       // creating the token and before requesting the page.
       global $base_url;
       $options =  array('external' => TRUE, 'absolute' => TRUE);
-
-      $this->assertResponse(403, 'Cannot access install.php with a "simpletest" user-agent header.');
       $curl_options = array(
         CURLOPT_HTTPGET => TRUE,
         CURLOPT_URL => url($base_url . '/core/install.php', $options),