I did reinstall the engine many times to verify it. The deb package is not infected - but when I installed the tgz package on my Debian machine the error was present. I think most people install the deb package.

The login code is:

 if ($query->param('op') eq 'login' && $$USER{node_id} != $HTMLVARS{gu
+est_user}) {
   5:   $str.= "Hey.  Glad you're back.  Would you like to go to your 
+" 
   6:     .linkNode($USER, "home node")
   7:     ." or to ".linkNode($HTMLVARS{default_node})."?<br>";
   8: 
   9:   $str.="...or back to "
  10:     .linkNode($query->param("lastnode_id"))
  11:     ."?<br>" if ($query->param("lastnode_id"));
  12:   return $str;
  13: } elsif ($query->param('op') eq 'login') { 
  14:   $str .="Oops.  You must have the wrong login or password or so
+mething:\n<P>\n";
  15: } elsif ($$USER{node_id} != $HTMLVARS{guest_user}) {
  16:   $str.="Hey, ".linkNode($USER)."...  this is where you log in:<
+p>\n";
  17: }else {
[cut]
[download]

So it must be that $$USER{node_id} != $HTMLVARS{guest_user} is not true for the Gods group member.