Tablesort used to output class=" active" for active columns with other...

Tablesort used to output class=" active" for active columns with other properties (align="right"). Now it correctly uses class="foo active" if a class 'foo' was specified, and class="active" otherwise.

includes/tablesort.inc

@@ -112,7 +112,12 @@ function tablesort_header($cell, $header, $ts) {
 function tablesort_cell($cell, $header, $ts, $i) {
   if ($header[$i]['data'] == $ts['name'] && $header[$i]['field']) {
     if (is_array($cell)) {
-      $cell['class'] .= ' active';
+      if (isset($cell['class'])) {
+        $cell['class'] .= ' active';
+      }
+      else {
+        $cell['class'] = 'active';
+      }
     }
     else {
       $cell = array('data' => $cell, 'class' => 'active');