Fix issue caused by non-default session.cookie_lifetime setting (#5961)

CHANGELOG

@@ -13,6 +13,7 @@ CHANGELOG Roundcube Webmail
 - Fix bug where mail search could return empty result on servers without SORT capability (#5973)
 - Fix bug where assets_path wasn't added to some watermark frames
 - Fix so untagged COPYUID responses are also supported according to RFC6851 (#5982)
+- Fix issue caused by non-default session.cookie_lifetime setting (#5961)
 
 RELEASE 1.3.1
 -------------

program/lib/Roundcube/rcube.php

@@ -515,6 +515,8 @@ class rcube
             ini_set('session.gc_maxlifetime', $lifetime * 2);
         }
 
+        // set session cookie lifetime so it never expires (#5961)
+        ini_set('session.cookie_lifetime', 0);
         ini_set('session.cookie_secure', $is_secure);
         ini_set('session.name', $sess_name ?: 'roundcube_sessid');
         ini_set('session.use_cookies', 1);