diff --git a/core/includes/form.inc b/core/includes/form.inc
index dfc1cb5..395cca7 100644
--- a/core/includes/form.inc
+++ b/core/includes/form.inc
@@ -3178,10 +3178,6 @@ function form_process_checkbox($element, $form_state) {
  * Processes a checkboxes form element.
  */
 function form_process_checkboxes($element) {
-  // The #type checkboxes element itself does not need validation.
-  // @todo Fix handling of values for checkboxes in programmed form submissions.
-  unset($element['#needs_validation']);
-
   $value = is_array($element['#value']) ? $element['#value'] : array();
   $element['#tree'] = TRUE;
   if (count($element['#options']) > 0) {
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
index b762889..912364e 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -644,9 +644,11 @@ abstract class WebTestBase extends TestBase {
               'pass2' => $this->root_user->pass_raw,
             ),
           ),
+          // form_type_checkboxes_value() requires NULL instead of FALSE values
+          // for programmatic form submissions to disable a checkbox.
           'update_status_module' => array(
-            1 => FALSE,
-            2 => FALSE,
+            1 => NULL,
+            2 => NULL,
           ),
         ),
       ),
@@ -660,21 +662,18 @@ abstract class WebTestBase extends TestBase {
     $batch = &batch_get();
     $batch = array();
 
-    // The installer sets/overrides some services to Null implementations, since
-    // there is no database yet. Thus, backup and restore the current $conf.
-    $originalConf = $conf;
-
     // Execute the non-interactive installer.
     require_once DRUPAL_ROOT . '/core/includes/install.core.inc';
     install_drupal($settings);
 
-    // Restore global $conf from before install_begin_request().
-    $conf = $originalConf;
-
     // Restore the original Simpletest batch.
     $batch = &batch_get();
     $batch = $this->originalBatch;
 
+    // Revert install_begin_request() cache and lock service overrides.
+    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);