Index: wp-includes/taxonomy-functions.php
===================================================================
--- wp-includes/taxonomy-functions.php	(revision 34843)
+++ wp-includes/taxonomy-functions.php	(working copy)
@@ -1485,6 +1485,8 @@
 		foreach ( $terms as $term ) {
 			$_terms[ $term->term_id ] = $term->slug;
 		}
+	} else {
+		$_terms = apply_filters( 'get_terms_fields_terms', $_terms, $_fields, $args, $taxonomies );
 	}
 
 	if ( ! empty( $_terms ) ) {