After logging out there is a triangle before the user name on the login screen as if the user is still logged in

I upgraded from Ubuntu 13.04 to 13.10 this morning.

On the login screen there usually only is a little triangle before each user that is currently logged in.

After starting up Ubuntu all users have no triangle before their names.

When I log in and return to the login screen afterwards (for example after having switched to another user) there is a little triangle before my user name indicating I am still logged in.

However when I log out the little triangle before my user name stays there although I am now logged out. This wasn't the case in Ubuntu 13.04.

So after a user has logged in there is no way to tell from the login screen whether the user is still logged in or not.

This is particularly annoying when you want to shut down the computer but a user is still logged in. Before you could see which user was still logged in (by looking which user had a triangle before his name indicating he was still logged in). Now it will be one of the users that have been logged in since the computer was started, but you don't know which user is still logged in and is preventing you to shut down.