Well, this is not really a bug , but:
When using session.auto_start , there is no way to load a 
class first, so session objects are pretty much not usable 
that way. I may be wrong, but I couldn't find any way to do 
it but doing a session_write_close(); session_start();

However this is not a solution because it wastes resources 
- writing the session files and opening it again for 
nothing. I belive that a session_reload() (or another 
solution for this case) should exist.