How come /sbin/nologin is in /etc/shells contradicting the man page?

[Bill Nottingham]

Matthias Clasen (mclasen at redhat.com) said: 
> The same issue has come up in gdm recently, where a database user showed
> up in the user list, because it was > 500 and had a "valid shell" (which
> was /sbin/nologin). We have changed gdm to not consider nologin a valid
> shell even if it is in /etc/shells.
> 
> This is all a bit of an undefined mess of traditional behaviours...

The database user shouldn't be > 500 ; that's a packaging bug.

Bill