PhpBrowser _closeSession doesn't close session.

[Naktibalda]

https://github.com/Codeception/Codeception/blob/2.2.2/src/Codeception/Module/PhpBrowser.php#L279

    public function _closeSession($session)
    {
        unset($session);
    }

All _closeSession does is unsetting a local variable.
To achieve desired effect, $session would have to be passed by reference and value overwritten instead of unsetting.

The only place where this method is called is https://github.com/Codeception/Codeception/blob/2.2.2/src/Codeception/Lib/Friend.php#L70

Update: _backupSession is fine.