Index: src/wp-includes/taxonomy.php
===================================================================
--- src/wp-includes/taxonomy.php	(revision 32909)
+++ src/wp-includes/taxonomy.php	(working copy)
@@ -1046,7 +1046,7 @@
 			'join'  => array(),
 		);
 
-		$join = '';
+		$join = $where = '';
 
 		$this->clean_query( $clause );