diff --git a/core/includes/install.core.inc b/core/includes/install.core.inc
index 03df556..eb558c2 100644
--- a/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -350,10 +350,8 @@ function install_begin_request(&$install_state) {
       drupal_bootstrap(DRUPAL_BOOTSTRAP_VARIABLES);
       _drupal_bootstrap_code();
     }
-    else {
-      drupal_bootstrap(DRUPAL_BOOTSTRAP_CODE);
-    }
     $kernel = new DrupalKernel('prod', TRUE, drupal_classloader(), FALSE);
+    $kernel->setBootstrapPhase($install_state['parameters']['bootstrap']);
     $kernel->boot();
 
     // We are anonymous until we reach install_configure_form_submit().
@@ -923,7 +921,8 @@ function install_system_rebuild(&$install_state) {
   // @see install_begin_request()
   drupal_bootstrap(DRUPAL_BOOTSTRAP_VARIABLES);
   _drupal_bootstrap_code();
-  $kernel = new DrupalKernel('prod', TRUE, drupal_classloader());
+  $kernel = new DrupalKernel('prod', TRUE, drupal_classloader(), FALSE);
+  $kernel->setBootstrapPhase(DRUPAL_BOOTSTRAP_VARIABLES);
   $kernel->boot();
 
   $install_state['base_system_verified'] = TRUE;
diff --git a/core/lib/Drupal/Core/DrupalKernel.php b/core/lib/Drupal/Core/DrupalKernel.php
index a5624d7..ac23479 100644
--- a/core/lib/Drupal/Core/DrupalKernel.php
+++ b/core/lib/Drupal/Core/DrupalKernel.php
@@ -114,6 +114,16 @@ class DrupalKernel extends Kernel implements DrupalKernelInterface {
   protected $containerNeedsDumping;
 
   /**
+   * The bootstrap phase to boot to.
+   *
+   * @todo Remove after converting session handling to a service.
+   * @see install_begin_request()
+   *
+   * @var integer
+   */
+  protected $bootstrapPhase = DRUPAL_BOOTSTRAP_CODE;
+
+  /**
    * Constructs a DrupalKernel object.
    *
    * @param string $environment
@@ -150,6 +160,16 @@ public function init() {
   }
 
   /**
+   * Sets the bootstrap phase to boot to.
+   *
+   * @todo Remove after converting session handling to a service.
+   * @see install_begin_request()
+   */
+  public function setBootstrapPhase($phase) {
+    $this->bootstrapPhase = $phase;
+  }
+
+  /**
    * Overrides Kernel::boot().
    */
   public function boot() {
@@ -160,7 +180,7 @@ public function boot() {
     $this->booted = TRUE;
     // @todo Remove this once everything in the bootstrap has been converted to
     //   services in the DIC.
-    drupal_bootstrap(DRUPAL_BOOTSTRAP_CODE);
+    drupal_bootstrap($this->bootstrapPhase);
     // Now that full bootstrap is complete, we can dump the container if it
     // was just rebuilt.
     if ($this->containerNeedsDumping && !$this->dumpDrupalContainer($this->container, $this->getContainerBaseClass())) {