Bug#544687: libpam-unix2: forks numerous instances of unix2_chkpwd

["Christoph Pleger" <Christoph.Pleger@cs.tu-dortmund.de>]

Hello,

though I obviously do not have the exactly same bug occurring, because the
corresponding change that introduced my bug took place two days after
Jakub's last message, I add my bug description to this report, because my
bug fits perfectly to the subject. That is, unix2_chkpwd is called
recursively again and again and the user cannot be authenticated.

The reason is that the user to be authenticated is from NIS and for this,
setting unix2_chkpwd to setgid shadow is definitely not sufficient. Please
make it setuid root again.

Regards
  Christoph