only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/migrate/migrate.install
@@ -0,0 +1,31 @@
+<?php
+
+/**
+ * @file
+ * Contains install and update functions for Migrate.
+ */
+
+/**
+ * @addtogroup updates-8.0.0-beta
+ * @{
+ */
+
+/**
+ * Remove load plugin references from existing migrations.
+ */
+function migrate_update_8001() {
+  $config_factory = \Drupal::configFactory();
+  foreach ($config_factory->listAll('migrate.migration.') as $migration_config_name) {
+    $migration = $config_factory->getEditable($migration_config_name);
+    if ($migration->get('load')) {
+      $migration->clear('load');
+      $migration->save(TRUE);
+    }
+  }
+
+  return t('Load plugin references removed.');
+}
+
+/**
+ * @} End of "addtogroup updates-8.0.0-beta".
+ */