[TYPO3] Problems with fe login when switching T3-4.0.4 -> T3-4.1.2

[Michael Rolli]

>
> Has anybody any idea where to begin to search? Anybody a hint what
I did some lowlevel investigation in the authentication service and  
did a little echo orgy in the function authUser() :-)
The result is very interesting:
$user contains the correct database record of my feuser. $this->login  
contains the correct stuff entered in the form. compareUident()  
therefor returns true as expected and authUser() itself returns true  
to the caller (btw, who is the caller?).

so, if authUser() returns true, why doesn't it work then?

Regards, Michael