Issue #3031130 by tim.plunkett:...

Issue #3031130 by tim.plunkett: \Drupal\Core\KeyValueStore\MemoryStorage::rename() erases data if keys match

(cherry picked from commit d70a4752)

core/lib/Drupal/Core/KeyValueStore/MemoryStorage.php

@@ -71,8 +71,10 @@ public function setMultiple(array $data) {
    * {@inheritdoc}
    */
   public function rename($key, $new_key) {
-    $this->data[$new_key] = $this->data[$key];
-    unset($this->data[$key]);
+    if ($key !== $new_key) {
+      $this->data[$new_key] = $this->data[$key];
+      unset($this->data[$key]);
+    }
   }
 
   /**

core/tests/Drupal/KernelTests/Core/KeyValueStore/StorageTestBase.php

@@ -189,6 +189,19 @@ public function testRename() {
     $this->assertNull($store->get('old'));
   }
 
+  /**
+   * Tests the rename operation.
+   */
+  public function testRenameNoChange() {
+    $stores = $this->createStorage();
+    $store = $stores[0];
+
+    $store->set('old', 'thing');
+    $this->assertSame($store->get('old'), 'thing');
+    $store->rename('old', 'old');
+    $this->assertSame($store->get('old'), 'thing');
+  }
+
   /**
    * Creates storage objects for each collection defined for this class.
    *