https://fedorahosted.org/sssd/ticket/2323
The functions that check for password expiration can return non-zero
return codes not only on internal failure, but also to indicate that the
password was expired. The code would in this case shortcut in the error
handler instead of making its way to the switch-case code below that
translates the SSSD error codes into PAM error codes.
We don't lose the error reporting, because any internal error would
translate into PAM_SYSTEM_ERROR anyway.