sudo fails for directory groups on 10.04

Binary package hint: sudo

This pertains to a fresh install and an upgrade of Ubuntu 10.04 server addition.

When using a directory for authentication (we use eDir), directory groups that are allowed to sudo in /etc/sudoers will get the following error:
$ sudo whoami
sudo: setreuid(ROOT_UID, user_uid): Operation not permitted

I've confirmed that /etc/sudoers is correct:

%<group name> ALL=(ALL) NOPASSWD: ALL

I am a member of said group.

WORKAROUND:
Install and start nscd.

# /etc/init.d/nscd start
 * Starting Name Service Cache Daemon nscd
   ...done.
<other terminal>
$ sudo whoami
root

nscd must be installed and running in order for directory groups to be allowed sudo privileges.

Some system info:
$ lsb_release -rd
Description: Ubuntu 10.04 LTS
Release: 10.04

$ apt-cache policy sudo
sudo:
  Installed: 1.7.2p1-1ubuntu5
  Candidate: 1.7.2p1-1ubuntu5
  Version table:
 *** 1.7.2p1-1ubuntu5 0
        500 http://us.archive.ubuntu.com/ubuntu/ lucid/main Packages
        100 /var/lib/dpkg/status

# dpkg -l '*ldap*'|grep ^ii
ii ldap-auth-client 0.5.2 meta-package for LDAP authentication
ii ldap-auth-config 0.5.2 Config package for LDAP authentication
ii ldap-utils 2.4.21-0ubuntu5 OpenLDAP utilities
ii libldap-2.4-2 2.4.21-0ubuntu5 OpenLDAP libraries
ii libnss-ldap 264-2ubuntu2 NSS module for using LDAP as a naming servic
ii libpam-ldap 184-8.2ubuntu1 Pluggable Authentication Module for LDAP

Thanks!

HippiePete