reverted:
--- b/core/modules/migrate/src/Plugin/Discovery/MigrateContainerDerivativeDiscoveryDecorator.php
+++ /dev/null
@@ -1,56 +0,0 @@
-<?php
-
-namespace Drupal\migrate\Plugin\Discovery;
-
-use Drupal\Component\Plugin\Discovery\DiscoveryInterface;
-use Drupal\Core\Extension\ModuleHandlerInterface;
-use Drupal\Core\Plugin\Discovery\ContainerDerivativeDiscoveryDecorator;
-
-class MigrateContainerDerivativeDiscoveryDecorator extends ContainerDerivativeDiscoveryDecorator {
-
-  /**
-   * The module handler to invoke the alter hook.
-   *
-   * @var \Drupal\Core\Extension\ModuleHandlerInterface
-   */
-  protected $moduleHandler;
-
-  /**
-   * Creates a new instance.
-   *
-   * @param \Drupal\Component\Plugin\Discovery\DiscoveryInterface $decorated
-   *   The parent object implementing DiscoveryInterface that is being
-   *   decorated.
-   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
-   *   The module handler.
-   */
-  public function __construct(DiscoveryInterface $decorated, ModuleHandlerInterface $module_handler) {
-    parent::__construct($decorated);
-    $this->moduleHandler = $module_handler;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function getDeriver($base_plugin_id, $base_definition) {
-    // Short-circuit attempts to instantiate derivers if the base provider is
-    // not available.
-    if (isset($base_definition['provider']) && !in_array($base_definition['provider'], array('core', 'component')) && !$this->providerExists($base_definition['provider'])) {
-      return NULL;
-    }
-    else {
-      return parent::getDeriver($base_plugin_id, $base_definition);
-    }
-  }
-
-  /**
-   * Determines if the provider of a definition exists.
-   *
-   * @return bool
-   *   TRUE if provider exists, FALSE otherwise.
-   */
-  protected function providerExists($provider) {
-    return $this->moduleHandler->moduleExists($provider);
-  }
-
-}
diff -u b/core/modules/migrate/src/Plugin/MigrationPluginManager.php b/core/modules/migrate/src/Plugin/MigrationPluginManager.php
--- b/core/modules/migrate/src/Plugin/MigrationPluginManager.php
+++ b/core/modules/migrate/src/Plugin/MigrationPluginManager.php
@@ -12,7 +12,6 @@
 use Drupal\Core\Plugin\Discovery\YamlDirectoryDiscovery;
 use Drupal\Core\Plugin\Factory\ContainerFactory;
 use Drupal\migrate\MigrateBuildDependencyInterface;
-use Drupal\migrate\Plugin\Discovery\MigrateContainerDerivativeDiscoveryDecorator;
 
 /**
  * Plugin manager for migration plugins.
@@ -69,7 +68,7 @@
       }, $this->moduleHandler->getModuleDirectories());
 
       $yaml_discovery = new YamlDirectoryDiscovery($directories, 'migrate');
-      $this->discovery = new MigrateContainerDerivativeDiscoveryDecorator($yaml_discovery, $this->moduleHandler);
+      $this->discovery = new ContainerDerivativeDiscoveryDecorator($yaml_discovery, $this->moduleHandler);
     }
     return $this->discovery;
   }
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Plugin/Discovery/ContainerDerivativeDiscoveryDecorator.php
+++ b/core/lib/Drupal/Core/Plugin/Discovery/ContainerDerivativeDiscoveryDecorator.php
@@ -3,15 +3,43 @@
 namespace Drupal\Core\Plugin\Discovery;
 
 use Drupal\Component\Plugin\Discovery\DerivativeDiscoveryDecorator;
+use Drupal\Component\Plugin\Discovery\DiscoveryInterface;
+use Drupal\Core\Extension\ModuleHandlerInterface;
 
 class ContainerDerivativeDiscoveryDecorator extends DerivativeDiscoveryDecorator {
 
   /**
+   * The module handler to validate the provider.
+   *
+   * @var \Drupal\Core\Extension\ModuleHandlerInterface
+   */
+  protected $moduleHandler;
+
+  /**
+   * Creates a new instance.
+   *
+   * @param \Drupal\Component\Plugin\Discovery\DiscoveryInterface $decorated
+   *   The parent object implementing DiscoveryInterface that is being
+   *   decorated.
+   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
+   *   The module handler.
+   */
+  public function __construct(DiscoveryInterface $decorated, ModuleHandlerInterface $module_handler) {
+    parent::__construct($decorated);
+    $this->moduleHandler = $module_handler;
+  }
+
+  /**
    * {@inheritdoc}
    */
   protected function getDeriver($base_plugin_id, $base_definition) {
     if (!isset($this->derivers[$base_plugin_id])) {
       $this->derivers[$base_plugin_id] = FALSE;
+      // Validate the provider first, to avoid attempting to create a deriver
+      // dependent on the provider.
+      if (isset($base_definition['provider']) && !in_array($base_definition['provider'], array('core', 'component')) && !$this->providerExists($base_definition['provider'])) {
+        return NULL;
+      }
       $class = $this->getDeriverClass($base_definition);
       if ($class) {
         // If the deriver provides a factory method, pass the container to it.
@@ -27,4 +55,14 @@ protected function getDeriver($base_plugin_id, $base_definition) {
     return $this->derivers[$base_plugin_id] ?: NULL;
   }
 
+  /**
+   * Determines if the provider of a definition exists.
+   *
+   * @return bool
+   *   TRUE if provider exists, FALSE otherwise.
+   */
+  protected function providerExists($provider) {
+    return $this->moduleHandler->moduleExists($provider);
+  }
+
 }