Cannot make use_strict_mode work with custom session handler upon 'files'

I want to implement custom session handler upon internal files handler similar to this: http://php.net/manual/en/class.sessionhandler.php#example-5380 (example 1). But with session.use_strict_mode = 1. I have been trying to test this sample code, but I can't seem to get it to work: --- session_module_name('files'); ini_set('session.use_strict_mode', '1'); class MySessionHandler extends SessionHandler{} session_set_save_handler(new MySessionHandler(), true); session_start(); var_dump(session_id()); --- After delete an existing session file and rerun script, it create new file with the same id. When there is no session_set_save_handler() it works as expected: new file is created with new id. I suppose that it is a bug, but maybe there is a solution that I can't see.