diff --git a/core/lib/Drupal/Core/Template/Attribute.php b/core/lib/Drupal/Core/Template/Attribute.php
index 8aaac3b..26a1793 100644
--- a/core/lib/Drupal/Core/Template/Attribute.php
+++ b/core/lib/Drupal/Core/Template/Attribute.php
@@ -117,11 +117,10 @@ public function offsetSet($name, $value) {
    *   An AttributeValueBase representation of the attribute's value.
    */
   protected function createAttributeValue($name, $value) {
-    // If the value is already an AttributeValueBase object,
-    // return a new instance of the same class, but with the new name.
+    // If the value is already an AttributeValueBase object, return it
+    // straight away.
     if ($value instanceof AttributeValueBase) {
-      $class = get_class($value);
-      return new $class($name, $value->value());
+      return $value;
     }
     // An array value or 'class' attribute name are forced to always be an
     // AttributeArray value for consistency.
diff --git a/core/modules/field/src/Plugin/migrate/source/d6/FieldInstance.php b/core/modules/field/src/Plugin/migrate/source/d6/FieldInstance.php
index 9235903..bddfc27 100644
--- a/core/modules/field/src/Plugin/migrate/source/d6/FieldInstance.php
+++ b/core/modules/field/src/Plugin/migrate/source/d6/FieldInstance.php
@@ -40,7 +40,7 @@ public function query() {
   public function fields() {
     return array(
       'field_name' => $this->t('The machine name of field.'),
-      'type_name' => $this->t('Content type where this field is in use.'),
+      'type_name' => $this->t('Content type where is used this field.'),
       'weight' => $this->t('Weight.'),
       'label' => $this->t('A name to show.'),
       'widget_type' => $this->t('Widget type.'),
diff --git a/core/modules/migrate/src/Entity/Migration.php b/core/modules/migrate/src/Entity/Migration.php
index 094713d..3ed050d 100644
--- a/core/modules/migrate/src/Entity/Migration.php
+++ b/core/modules/migrate/src/Entity/Migration.php
@@ -320,10 +320,10 @@ protected function getProcessNormalized(array $process) {
    * {@inheritdoc}
    */
   public function getDestinationPlugin($stub_being_requested = FALSE) {
+    if ($stub_being_requested && !empty($this->destination['no_stub'])) {
+      throw new MigrateSkipRowException;
+    }
     if (!isset($this->destinationPlugin)) {
-      if ($stub_being_requested && !empty($this->destination['no_stub'])) {
-        throw new MigrateSkipRowException;
-      }
       $this->destinationPlugin = \Drupal::service('plugin.manager.migrate.destination')->createInstance($this->destination['plugin'], $this->destination, $this);
     }
     return $this->destinationPlugin;
diff --git a/core/modules/migrate_drupal/src/Tests/StubTestTrait.php b/core/modules/migrate_drupal/src/Tests/StubTestTrait.php
index 1e028bf..fe48cd9 100644
--- a/core/modules/migrate_drupal/src/Tests/StubTestTrait.php
+++ b/core/modules/migrate_drupal/src/Tests/StubTestTrait.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\migrate_drupal\Tests;
 use Drupal\migrate\Entity\Migration;
+use Drupal\migrate\MigrateSkipRowException;
 use Drupal\migrate\Row;
 
 /**
@@ -20,18 +21,36 @@
    *
    * @param string $entity_type_id
    *   The entity type we are stubbing.
+   * @param boolean $no_stub
+   *   TRUE to prevent stub creation.
    */
-  protected function performStubTest($entity_type_id) {
-    $entity_id = $this->createStub($entity_type_id);
-    $this->assertTrue($entity_id, 'Stub successfully created');
-    if ($entity_id) {
-      $violations = $this->validateStub($entity_type_id, $entity_id);
-      if (!$this->assertIdentical(count($violations), 0, 'Stub is a valid entity')) {
-        foreach ($violations as $violation) {
-          $this->fail((string) $violation->getMessage());
+  protected function performStubTest($entity_type_id, $no_stub = FALSE) {
+    try {
+      $entity_id = $this->createStub($entity_type_id, $no_stub);
+      if ($no_stub) {
+        $this->fail('Stub creation suppressed');
+      }
+      else {
+        $this->assertTrue($entity_id, 'Stub successfully created');
+        if ($entity_id) {
+          $violations = $this->validateStub($entity_type_id, $entity_id);
+          if (!$this->assertIdentical(count($violations), 0, 'Stub is a valid entity')) {
+            foreach ($violations as $violation) {
+              $this->fail((string) $violation->getMessage());
+            }
+          }
         }
       }
     }
+    catch (MigrateSkipRowException $e) {
+      if ($no_stub) {
+        $this->pass('Stub creation suppressed');
+      }
+      else {
+        $this->fail('Stub successfully created');
+      }
+    }
+
   }
 
   /**
@@ -39,11 +58,13 @@ protected function performStubTest($entity_type_id) {
    *
    * @param string $entity_type_id
    *   The entity type we are stubbing.
+   * @param boolean $no_stub
+   *   TRUE to prevent stub creation.
    *
    * @return int
    *   ID of the created entity.
    */
-  protected function createStub($entity_type_id) {
+  protected function createStub($entity_type_id, $no_stub = FALSE) {
     // Create a dummy migration to pass to the destination plugin.
     $config = [
       'id' => 'dummy',
@@ -52,7 +73,12 @@ protected function createStub($entity_type_id) {
       'process' => [],
       'destination' => ['plugin' => 'entity:' . $entity_type_id],
     ];
+    if ($no_stub) {
+      $config['destination']['no_stub'] = TRUE;
+    }
     $migration = Migration::create($config);
+    // An initial normal fetch of the destination plugin to cache it.
+    $migration->getDestinationPlugin();
     $destination_plugin = $migration->getDestinationPlugin(TRUE);
     $stub_row = new Row([], [], TRUE);
     $destination_ids = $destination_plugin->import($stub_row);
diff --git a/core/modules/migrate_drupal/tests/fixtures/drupal7.php b/core/modules/migrate_drupal/tests/fixtures/drupal7.php
index 78651e4..c1480c1 100644
--- a/core/modules/migrate_drupal/tests/fixtures/drupal7.php
+++ b/core/modules/migrate_drupal/tests/fixtures/drupal7.php
@@ -41540,30 +41540,10 @@
   'value' => 'i:999;',
 ))
 ->values(array(
-  'name' => 'update_check_frequency',
-  'value' => 'i:1;',
-))
-->values(array(
-  'name' => 'update_fetch_url',
-  'value' => 's:23:"http://127.0.0.1/update";',
-))
-->values(array(
   'name' => 'update_last_check',
   'value' => 'i:1444944973;',
 ))
 ->values(array(
-  'name' => 'update_max_fetch_attempts',
-  'value' => 'i:3;',
-))
-->values(array(
-  'name' => 'update_notification_threshold',
-  'value' => 's:3:"all";',
-))
-->values(array(
-  'name' => 'update_notify_emails',
-  'value' => 'a:1:{i:0;s:19:"webmaster@127.0.0.1";}',
-))
-->values(array(
   'name' => 'user_admin_role',
   'value' => 's:1:"3";',
 ))
diff --git a/core/modules/node/src/Tests/Migrate/MigrateNodeStubTest.php b/core/modules/node/src/Tests/Migrate/MigrateNodeStubTest.php
index 22d140b..8127942 100644
--- a/core/modules/node/src/Tests/Migrate/MigrateNodeStubTest.php
+++ b/core/modules/node/src/Tests/Migrate/MigrateNodeStubTest.php
@@ -45,4 +45,11 @@ public function testStub() {
     $this->performStubTest('node');
   }
 
+  /**
+   * Tests suppression of node stubs.
+   */
+  public function testNoStub() {
+    $this->performStubTest('node', TRUE);
+  }
+
 }
diff --git a/core/modules/update/migration_templates/d6_update_settings.yml b/core/modules/update/migration_templates/d6_update_settings.yml
new file mode 100644
index 0000000..37e0ef1
--- /dev/null
+++ b/core/modules/update/migration_templates/d6_update_settings.yml
@@ -0,0 +1,21 @@
+id: d6_update_settings
+label: Update configuration
+migration_tags:
+  - Drupal 6
+source:
+  plugin: variable
+  variables:
+    - update_max_fetch_attempts
+    - update_fetch_url
+    - update_notification_threshold
+    - update_notify_emails
+    - update_check_frequency
+process:
+  'fetch/max_attempts': update_max_fetch_attempts
+  'fetch/url': update_fetch_url
+  'notification/threshold': update_notification_threshold
+  'notification/emails': update_notify_emails
+  'check/interval_days': update_check_frequency
+destination:
+  plugin: config
+  config_name: update.settings
diff --git a/core/modules/update/migration_templates/update_settings.yml b/core/modules/update/migration_templates/update_settings.yml
deleted file mode 100644
index ad22472..0000000
--- a/core/modules/update/migration_templates/update_settings.yml
+++ /dev/null
@@ -1,22 +0,0 @@
-id: update_settings
-label: Update configuration
-migration_tags:
-  - Drupal 6
-  - Drupal 7
-source:
-  plugin: variable
-  variables:
-    - update_max_fetch_attempts
-    - update_fetch_url
-    - update_notification_threshold
-    - update_notify_emails
-    - update_check_frequency
-process:
-  'fetch/max_attempts': update_max_fetch_attempts
-  'fetch/url': update_fetch_url
-  'notification/threshold': update_notification_threshold
-  'notification/emails': update_notify_emails
-  'check/interval_days': update_check_frequency
-destination:
-  plugin: config
-  config_name: update.settings
diff --git a/core/modules/update/src/Tests/Migrate/d6/MigrateUpdateConfigsTest.php b/core/modules/update/src/Tests/Migrate/d6/MigrateUpdateConfigsTest.php
index 29cf502..679350a 100644
--- a/core/modules/update/src/Tests/Migrate/d6/MigrateUpdateConfigsTest.php
+++ b/core/modules/update/src/Tests/Migrate/d6/MigrateUpdateConfigsTest.php
@@ -29,7 +29,7 @@ class MigrateUpdateConfigsTest extends MigrateDrupal6TestBase {
    */
   protected function setUp() {
     parent::setUp();
-    $this->executeMigration('update_settings');
+    $this->executeMigration('d6_update_settings');
   }
 
   /**
diff --git a/core/tests/Drupal/Tests/Core/Common/AttributesTest.php b/core/tests/Drupal/Tests/Core/Common/AttributesTest.php
index 4fc57ae..1dafef9 100644
--- a/core/tests/Drupal/Tests/Core/Common/AttributesTest.php
+++ b/core/tests/Drupal/Tests/Core/Common/AttributesTest.php
@@ -71,20 +71,4 @@ public function testAttributeIteration() {
     }
   }
 
-  /**
-   * Test AttributeValueBase copy.
-   */
-  public function testAttributeValueBaseCopy() {
-    $original_attributes = new Attribute([
-      'checked' => TRUE,
-      'class' => ['who', 'is', 'on'],
-      'id' => 'first',
-    ]);
-    $attributes['selected'] = $original_attributes['checked'];
-    $attributes['id'] = $original_attributes['id'];
-    $attributes = new Attribute($attributes);
-    $this->assertSame((string) $original_attributes, ' checked class="who is on" id="first"', 'Original boolean value used with original name.');
-    $this->assertSame((string) $attributes, ' selected id="first"', 'Original boolean value used with new name.');
-  }
-
 }