Steps to reproduce the issue

Login with 'Remember Me' enabled.
Delete frontend session cookie and leave remember-me cookie only to simulate session cookie expiration.
Load any page, see that user was actually auto-logged in: user in session is OK (see in debug console), user is displayed in backend logged-in users module etc.

Now visit Users->Login Form menu item, see login form instead of Log Out button

Expected result

Users->Login Form should display Log Out button

Actual result

Users->Login Form should displays login form even though the user is logged in