Ticket #11878: 11878.2.patch

wp-includes/post-template.php

@@ -304 +304 @@
  * @return array Array of classes.
  */
 function get_post_class( $class = '', $post_id = null ) {
+        if ( is_null($post_id) )
+                $post_id = get_the_ID();
+
         $post = get_post($post_id);
 
         $classes = array();