MDL-13043 get_users_listing() always returned the guest account, which was then used in the user count on this page. I made this inclusion conditional, and the bug disappeared.

lib/datalib.php

@@ -266,12 +266,13 @@ function get_users($get=true, $search='', $confirmed=false, $exceptions='', $sor
  * @param string $search ?
  * @param string $firstinitial ?
  * @param string $lastinitial ?
+ * @param bool $includeguest By default, returns the guest user account as well. If set to false, it will not be returned.
  * @returnobject {@link $USER} records
  * @todo Finish documenting this function
  */
 
 function get_users_listing($sort='lastaccess', $dir='ASC', $page=0, $recordsperpage=0,
-                           $search='', $firstinitial='', $lastinitial='', $remotewhere='') {
+                           $search='', $firstinitial='', $lastinitial='', $remotewhere='', $includeguest=true) {
 
     global $CFG;
 
@@ -280,6 +281,10 @@ function get_users_listing($sort='lastaccess', $dir='ASC', $page=0, $recordsperp
 
     $select = "deleted <> '1'";
 
+    if (!$includeguest) {
+        $select .= ' AND username <> \'guest\'';
+    }
+
     if (!empty($search)) {
         $search = trim($search);
         $select .= " AND ($fullname $LIKE '%$search%' OR email $LIKE '%$search%') ";