Index: wp-includes/category-template.php
===================================================================
--- wp-includes/category-template.php	(revision 16880)
+++ wp-includes/category-template.php	(working copy)
@@ -67,6 +67,8 @@
 	$categories = get_the_terms( $id, 'category' );
 	if ( ! $categories )
 		$categories = array();
+	
+	$categories = array_values( $categories );
 
 	foreach ( array_keys( $categories ) as $key ) {
 		_make_cat_compat( $categories[$key] );