diff --git a/core/lib/Drupal/Core/Entity/ContentEntityBase.php b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
index c03266f..7c0c711 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityBase.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
@@ -163,6 +163,13 @@
   protected $validationRequired = FALSE;
 
   /**
+   * The original revision id before the new revision was set.
+   *
+   * @var int
+   */
+  protected $originalRevisionId;
+
+  /**
    * {@inheritdoc}
    */
   public function __construct(array $values, $entity_type, $bundle = FALSE, $translations = array()) {
@@ -266,7 +273,7 @@ public function setNewRevision($value = TRUE) {
     if ($value && !$this->newRevision) {
       // When saving a new revision, set any existing revision ID to NULL so as
       // to ensure that a new revision will actually be created.
-      $this->original_revision = $this->getRevisionId();
+      $this->originalRevisionId = $this->getRevisionId();
       $this->set($this->getEntityType()->getKey('revision'), NULL);
 
       // Make sure that the flag tracking which translations are affected by the
@@ -286,19 +293,23 @@ public function setNewRevision($value = TRUE) {
    * {@inheritdoc}
    */
   public function getOriginalRevisionId() {
-    if (isset($this->original_revision)) {
-      return $this->original_revision;
+    $revison_id = $this->originalRevisionId;
+    if (!$revison_id) {
+      $revison_id = $this->getRevisionId();
     }
+    return $revison_id;
   }
 
   /**
    * {@inheritdoc}
    */
   public function loadUnchangedRevision() {
-    $storage = $this->entityTypeManager()
-      ->getStorage($this->entityTypeId);
-    $storage->resetCache([$this->id()]);
-    return $storage->loadRevision($this->getOriginalRevisionId());
+    if ($this->getOriginalRevisionId()) {
+      $storage = $this->entityTypeManager()
+        ->getStorage($this->entityTypeId);
+      $storage->resetCache([$this->id()]);
+      return $storage->loadRevision($this->getOriginalRevisionId());
+    }
   }
 
   /**