Merge pull request #215 from enricocavalli/patch-1

Corrected logic in checkSessionCookie

lib/SimpleSAML/Utils/HTTP.php

@@ -271,7 +271,7 @@ class HTTP
      */
     public static function checkSessionCookie($retryURL = null)
     {
-        if (!is_string($retryURL) || !is_null($retryURL)) {
+        if (!is_string($retryURL) && !is_null($retryURL)) {
             throw new \InvalidArgumentException('Invalid input parameters.');
         }
 
@@ -1024,4 +1024,4 @@ class HTTP
         $p->show();
         exit(0);
     }
-}
+}
\ No newline at end of file