Fixed bug in filtering IdPs on DS

* Fixed bug in filtering IdPs on DS from the commit: 71bebba
* Problem: Result of method doFilter was not assigned to var

(cherry picked from commit c8ecdf9)

Author: vyskocilpavel

CHANGELOG.md

@@ -2,6 +2,8 @@
 All notable changes to this project will be documented in this file.
 
 ## [Unreleased]
+#### Fixed
+- Fixed bug in filtering IdPs on DS
 
 ## [v3.5.0]
 #### Changed

lib/Disco.php

@@ -149,7 +149,7 @@ protected function filterList($list)
             || !$this->originalsp['disco.doNotFilterIdps']
         ) {
             $list = parent::filterList($list);
-            self::doFilter($list, $disableWhitelisting, $this->scopedIDPList);
+            $list = self::doFilter($list, $disableWhitelisting, $this->scopedIDPList);
             $list = $this->greylistingPerSP($list, $this->originalsp);
         }