gistfile1.patch

diff --git a/core/lib/Drupal/Core/Entity/ContentEntityType.php b/core/lib/Drupal/Core/Entity/ContentEntityType.php
index 5be34c9ba5..145350e037 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityType.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityType.php
@@ -25,8 +25,11 @@ public function __construct($definition) {
       'view_builder' => 'Drupal\Core\Entity\EntityViewBuilder',
     ];
 
+    // Only new instances should provide the default revision metadata keys.
+    // The stored instances should return only what already has been stored
+    // under the property $revision_metadata_keys.
     $this->revision_metadata_keys += [
-      'revision_default' => 'revision_default',
+      'revision_default' => 'revision_default'
     ];
   }
 
@@ -59,7 +62,10 @@ protected function checkStorageClass($class) {
   public function getRevisionMetadataKeys($include_backwards_compatibility_field_names = TRUE) {
     // Provide backwards compatibility in case the revision metadata keys are
     // not defined in the entity annotation.
-    if (!$this->revision_metadata_keys && $include_backwards_compatibility_field_names) {
+    $required_revision_metadata_keys = [
+      'revision_default' => 'revision_default'
+    ];
+    if ((!$this->revision_metadata_keys || ($this->revision_metadata_keys === $required_revision_metadata_keys)) && $include_backwards_compatibility_field_names) {
       $base_fields = \Drupal::service('entity_field.manager')->getBaseFieldDefinitions($this->id());
       if ((isset($base_fields['revision_uid']) && $revision_user = 'revision_uid') || (isset($base_fields['revision_user']) && $revision_user = 'revision_user')) {
         @trigger_error('The revision_user revision metadata key is not set.', E_USER_DEPRECATED);
diff --git a/core/lib/Drupal/Core/Entity/EntityFieldManager.php b/core/lib/Drupal/Core/Entity/EntityFieldManager.php
index c19956491d..025d92cca1 100644
--- a/core/lib/Drupal/Core/Entity/EntityFieldManager.php
+++ b/core/lib/Drupal/Core/Entity/EntityFieldManager.php
@@ -224,7 +224,9 @@ protected function buildBaseFieldDefinitions($entity_type_id) {
 
     // Make sure that revisionable entity types are correctly defined.
     if ($entity_type->isRevisionable()) {
-      $field_name = $entity_type->getRevisionMetadataKey('revision_default');
+      // Disable the BC layer to prevent a recursion, this only needs the
+      // revision_default key that is always set.
+      $field_name = $entity_type->getRevisionMetadataKeys(FALSE)['revision_default'];
       $base_field_definitions[$field_name] = BaseFieldDefinition::create('boolean')
         ->setLabel($this->t('Default revision'))
         ->setDescription($this->t('A flag indicating whether this was a default revision when it was saved.'))
diff --git a/core/modules/system/tests/modules/entity_test_revlog/src/Entity/EntityTestMulWithRevisionLog.php b/core/modules/system/tests/modules/entity_test_revlog/src/Entity/EntityTestMulWithRevisionLog.php
index 5a17b858dc..cb9c7bbc0c 100644
--- a/core/modules/system/tests/modules/entity_test_revlog/src/Entity/EntityTestMulWithRevisionLog.php
+++ b/core/modules/system/tests/modules/entity_test_revlog/src/Entity/EntityTestMulWithRevisionLog.php
@@ -5,6 +5,9 @@
 /**
  * Defines the test entity class.
  *
+ * This entity type does not define revision_metadata_keys on purpose to test
+ * the BC layer.
+ *
  * @ContentEntityType(
  *   id = "entity_test_mul_revlog",
  *   label = @Translation("Test entity - data table, revisions log"),
@@ -21,11 +24,6 @@
  *     "label" = "name",
  *     "langcode" = "langcode",
  *   },
- *   revision_metadata_keys = {
- *     "revision_user" = "revision_user",
- *     "revision_created" = "revision_created",
- *     "revision_log_message" = "revision_log_message"
- *   },
  * )
  */
 class EntityTestMulWithRevisionLog extends EntityTestWithRevisionLog {