package gnome-session 3.11.4-0ubuntu1~trusty2 [origin: LP-PPA-gnome3-team-gnome3-staging] failed to install/upgrade: tentative de remplacement de « /usr/share/upstart/sessions/gnome-session.conf », qui appartient aussi au paquet gnome-session-bin 3.9.90-0ubuntu12

On startup

ProblemType: Package
DistroRelease: Ubuntu 14.04
Package: gnome-session 3.11.4-0ubuntu1~trusty2 [origin: LP-PPA-gnome3-team-gnome3-staging]
ProcVersionSignature: Ubuntu 3.13.0-23.45-generic 3.13.8
Uname: Linux 3.13.0-23-generic x86_64
ApportVersion: 2.14.1-0ubuntu1
Architecture: amd64
Date: Tue Apr 8 17:18:35 2014
DuplicateSignature: package:gnome-session:3.11.4-0ubuntu1~trusty2 [origin: LP-PPA-gnome3-team-gnome3-staging]:tentative de remplacement de « /usr/share/upstart/sessions/gnome-session.conf », qui appartient aussi au paquet gnome-session-bin 3.9.90-0ubuntu12
ErrorMessage: tentative de remplacement de « /usr/share/upstart/sessions/gnome-session.conf », qui appartient aussi au paquet gnome-session-bin 3.9.90-0ubuntu12
InstallationDate: Installed on 2014-04-07 (1 days ago)
InstallationMedia: Ubuntu-GNOME 14.04 LTS "Trusty Tahr" - Beta amd64 (20140326.1)
PackageArchitecture: all
SourcePackage: gnome-session
Title: package gnome-session 3.11.4-0ubuntu1~trusty2 [origin: LP-PPA-gnome3-team-gnome3-staging] failed to install/upgrade: tentative de remplacement de « /usr/share/upstart/sessions/gnome-session.conf », qui appartient aussi au paquet gnome-session-bin 3.9.90-0ubuntu12
UpgradeStatus: No upgrade log present (probably fresh install)