Index: src/wp-includes/class-wp-term-query.php
===================================================================
--- src/wp-includes/class-wp-term-query.php	(revision 39624)
+++ src/wp-includes/class-wp-term-query.php	(working copy)
@@ -305,7 +305,7 @@
 		global $wpdb;
 
 		$this->parse_query( $this->query_vars );
-		$args = $this->query_vars;
+		$args = &$this->query_vars;
 
 		// Set up meta_query so it's available to 'pre_get_terms'.
 		$this->meta_query = new WP_Meta_Query();