[Samba] What exactly is this?

[Chris Nighswonger]

Could someone comment on whether or not this "WARNING" is valid?

[2014/12/24 14:02:46.078767,  2]
auth/token_util.c:479(finalize_local_nt_token)
  WARNING: Failed to create BUILTIN\Users group! Can Winbind allocate gids?

My Samba DC has been working fine for the past couple of years even with
this in the logs, but curiosity has gotten the better of me at this point.
Google seems to indicate that others have wondered about this same
question, but never received an answer.

System info:

root at biblios:/var/lib/samba/netlogon# lsb_release -a
No LSB modules are available.
Distributor ID:    Ubuntu
Description:    Ubuntu 13.04
Release:    13.04
Codename:    raring

root at biblios:/var/lib/samba/netlogon# nmbd -V
Version 3.6.9

root at biblios:/var/lib/samba/netlogon# smbd -V
Version 3.6.9

root at biblios:/var/lib/samba/netlogon# slapd -V
@(#) $OpenLDAP: slapd  (Jun 20 2013 17:11:18) $
    buildd at allspice:/build/buildd/openldap-2.4.31/debian/build/servers/slapd

Samba log level = 2