commit 6314b41a588535ddf66cc7850e6549ddfbcf29a1
Author: Andrew Morton <amorton@forumone.com>
Date:   Sat Aug 15 11:34:35 2015 -0700

    42273: Fix checkbox classess for active facet in gesso

diff --git a/public/sites/all/themes/gesso/includes/facetapi.inc b/public/sites/all/themes/gesso/includes/facetapi.inc
index 6cf7b3f..e947812 100644
--- a/public/sites/all/themes/gesso/includes/facetapi.inc
+++ b/public/sites/all/themes/gesso/includes/facetapi.inc
@@ -43,11 +43,10 @@ function gesso_facetapi_link_active($vars) {
   // Sets options to HTML since we already sanitized the link text.
   $vars['options']['html'] = TRUE;
 
-  // Change link classes.
-  $vars['options']['attributes']['class'] = array(
-    'facet',
-    'is-active',
-  );
+  // Add link classes.
+  $vars['options']['attributes']['class'] = array_merge(
+    $vars['options']['attributes']['class'],
+    array('facet', 'is-active'));
 
   return theme_link($vars);
 }