Assertion failure

[João Pinto]

After upgrading to precie when using sudo I get the following warning:
sudo: pam_mount.c:417: modify_pm_count: Assertion `user != ((void *)0)' failed.

janito@jpinto-desktop:/tmp$ sudo echo test
test
sudo: pam_mount.c:417: modify_pm_count: Assertion `user != ((void *)0)' failed.
Abortado

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: sudo 1.8.3p1-1ubuntu3
ProcVersionSignature: Ubuntu 3.2.0-22.35-generic 3.2.14
Uname: Linux 3.2.0-22-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.0-0ubuntu5
Architecture: amd64
Date: Sun Apr 15 19:36:34 2012
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
ProcEnviron:
 SHELL=/bin/bash
 TERM=xterm
 PATH=(custom, user)
 LANG=pt_PT.UTF-8
 LANGUAGE=pt:pt_BR:en
SourcePackage: sudo
UpgradeStatus: Upgraded to precise on 2011-12-01 (135 days ago)
VisudoCheck: /etc/sudoers: parsed OK