diff -u b/core/lib/Drupal/Core/DependencyInjection/UpdateDependenciesTrait.php b/core/lib/Drupal/Core/DependencyInjection/UpdateDependenciesTrait.php
--- b/core/lib/Drupal/Core/DependencyInjection/UpdateDependenciesTrait.php
+++ b/core/lib/Drupal/Core/DependencyInjection/UpdateDependenciesTrait.php
@@ -2,10 +2,11 @@
 
 /**
  * @file
- * Contains \Drupal\Core\DependencyInjection\DependencyReinjectionTrait.
+ * Contains \Drupal\Core\DependencyInjection\UpdateDependenciesTrait.
  */
 
 namespace Drupal\Core\DependencyInjection;
+
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
@@ -18,10 +19,15 @@
 trait UpdateDependenciesTrait {
 
   /**
-   * Updates all external dependencies and refetch them from the container.
+   * Updates an object's external dependencies from the container.
+   *
+   * This method depends on \Drupal\Core\DependencyInjection\Container::get()
+   * adding the _serviceId property to all services.
    *
    * @param \Symfony\Component\DependencyInjection\ContainerInterface $container
    *   The container.
+   *
+   * @see \Drupal\Core\DependencyInjection\Container
    */
   protected function updateDependencies(ContainerInterface $container) {
     $vars = get_object_vars($this);
@@ -29,6 +35,10 @@
       if (is_object($value) && isset($value->_serviceId)) {
         $this->$key = $container->get($value->_serviceId);
       }
+      // Special case the container, which might not have a service ID.
+      elseif ($value instanceof ContainerInterface) {
+        $this->$key = $container;
+      }
     }
   }
 
only in patch2:
unchanged:
--- /dev/null
+++ b/core/tests/Drupal/Tests/Core/DependencyInjection/UpdateDependenciesTraitTest.php
@@ -0,0 +1,46 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\DependencyInjection\UpdateDependenciesTraitTest.
+ */
+
+namespace Drupal\Tests\Core\DependencyInjection;
+
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * @coversDefaultClass \Drupal\Core\DependencyInjection\UpdateDependenciesTrait
+ * @group DependencyInjection
+ */
+class UpdateDependenciesTraitTest extends UnitTestCase {
+
+  /**
+   * @covers ::updateDependencies
+   */
+  public function testUpdateDependencies() {
+    $service = new \StdClass();
+    $service->_serviceId = 'test_service';
+    $container = $this->getMock('Symfony\Component\DependencyInjection\ContainerInterface');
+    $container->expects($this->any())
+      ->method('get')
+      ->with('test_service')
+      ->willReturn($service);
+
+    $trait = $this->getMockForTrait('Drupal\Core\DependencyInjection\UpdateDependenciesTrait');
+    $trait->dependency = clone $service;
+    $trait->container = clone $container;
+    $object = new \StdClass();
+    $trait->object = $object;
+
+    $update_dependencies_method = new \ReflectionMethod($trait, 'updateDependencies');
+    $update_dependencies_method->setAccessible(TRUE);
+
+    // Ensure that the service and container are updated but other objects are
+    // untouched.
+    $update_dependencies_method->invoke($trait, $container);
+    $this->assertSame($service, $trait->dependency);
+    $this->assertSame($container, $trait->container);
+    $this->assertSame($object, $trait->object);
+  }
+}