package sudo 1.8.5p2-1ubuntu1.1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1

[Lebret Jean-Michel]

impossible de charger le paquet de mise à jour

ProblemType: Package
DistroRelease: Ubuntu 12.10
Package: sudo 1.8.5p2-1ubuntu1.1
ProcVersionSignature: Ubuntu 3.5.0-25.39-generic 3.5.7.4
Uname: Linux 3.5.0-25-generic i686
ApportVersion: 2.6.1-0ubuntu10
Architecture: i386
Date: Fri Mar 1 13:46:57 2013
DpkgHistoryLog:
 Start-Date: 2013-03-01 13:46:36
 Commandline: aptdaemon role='role-commit-packages' sender=':1.113'
 Upgrade: firefox-globalmenu:i386 (19.0+build1-0ubuntu0.12.10.1, 19.0+build1-0ubuntu0.12.10.2), firefox:i386 (19.0+build1-0ubuntu0.12.10.1, 19.0+build1-0ubuntu0.12.10.2), sudo:i386 (1.8.5p2-1ubuntu1, 1.8.5p2-1ubuntu1.1), firefox-gnome-support:i386 (19.0+build1-0ubuntu0.12.10.1, 19.0+build1-0ubuntu0.12.10.2), firefox-locale-en:i386 (19.0+build1-0ubuntu0.12.10.1, 19.0+build1-0ubuntu0.12.10.2), firefox-locale-fr:i386 (19.0+build1-0ubuntu0.12.10.1, 19.0+build1-0ubuntu0.12.10.2), openssl:i386 (1.0.1c-3ubuntu2.1, 1.0.1c-3ubuntu2.2), libssl1.0.0:i386 (1.0.1c-3ubuntu2.1, 1.0.1c-3ubuntu2.2)
DuplicateSignature:
 Setting up sudo (1.8.5p2-1ubuntu1.1) ...
 chown: groupe non valide: «root:root»
 dpkg: error processing sudo (--configure):
  subprocess installed post-installation script returned error exit status 1
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationDate: Installed on 2013-01-12 (47 days ago)
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release i386 (20121017.2)
MarkForUpload: True
SourcePackage: sudo
Title: package sudo 1.8.5p2-1ubuntu1.1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)
VisudoCheck:
 /etc/sudoers: parsed OK
 /etc/sudoers.d/README: parsed OK