Ticket #38442: patch-wp-query.txt

--- /wp-includes/query.php      2016-10-19 16:02:27.728266004 +0200
+++ /wp-includes/query.php      2016-10-22 10:00:49.000000000 +0200
@@ -2333,7 +2333,21 @@
                $primary_meta_query = false;
                $meta_clauses = $this->meta_query->get_clauses();
                if ( ! empty( $meta_clauses ) ) {
-                       $primary_meta_query = reset( $meta_clauses );
+
+                       /* start : patch - find the primary_meta_query by 'orderby key' */
+
+                       $primary_meta_query = false;
+                       foreach( $meta_clauses as $meta_clause ) {
+                               if ( $meta_clause['key'] == $orderby ) {
+                                       $primary_meta_query = $meta_clause;
+                                       break;
+                               }
+                       }
+                       if( ! $primary_meta_query ) {
+                               $primary_meta_query = reset( $meta_clauses );
+                       }
+
+                       /* end : patch */
 
                        if ( ! empty( $primary_meta_query['key'] ) ) {
                                $primary_meta_key = $primary_meta_query['key'];