Ticket #17850: 17850.diff

wp-includes/meta.php

@@ -588 +588 @@
  * @return bool True if the key is protected, false otherwise.
  */
 function is_protected_meta( $meta_key, $meta_type = null ) {
-        $protected = (  '_' == $meta_key[0] );
+        $protected = false;
+        $protected_keys = array( '_edit_last', '_edit_lock', '_thumbnail_id' );
 
+        if ( 0 === strpos( $meta_key, '_wp_' ) || 0 === strpos( $meta_key, '_menu_item_' ) || in_array( $meta_key, $protected_keys ) )
+                $protected = true;
+
         return apply_filters( 'is_protected_meta', $protected, $meta_key, $meta_type );
 }