MDL-47371 block_navigation: Don't double escape course titles

lib/navigationlib.php

@@ -2458,9 +2458,7 @@ class global_navigation extends navigation_node {
 
         $coursenode = $parent->add($coursename, $url, self::TYPE_COURSE, $shortname, $course->id);
         $coursenode->hidden = (!$course->visible);
-        // We need to decode &'s here as they will have been added by format_string above and attributes will be encoded again
-        // later.
-        $coursenode->title(str_replace('&', '&', $fullname));
+        $coursenode->title(format_string($course->fullname, true, array('context' => $coursecontext, 'escape' => false)));
         if ($canexpandcourse) {
             // This course can be expanded by the user, make it a branch to make the system aware that its expandable by ajax.
             $coursenode->nodetype = self::NODETYPE_BRANCH;