package kaccounts-providers (not installed) failed to install/upgrade: tentative de remplacement de « /etc/signon-ui/webkit-options.d/www.facebook.com.conf », qui appartient aussi au paquet account-plugin-facebook 0.12+16.04.20160126-0ubuntu1

I was trying to install kubuntu-desktop from an Unity session, kubuntu-backports ppa already activated…

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: kaccounts-providers (not installed)
ProcVersionSignature: Ubuntu 4.4.0-31.50-generic 4.4.13
Uname: Linux 4.4.0-31-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
Date: Tue Aug 2 01:33:52 2016
ErrorMessage: tentative de remplacement de « /etc/signon-ui/webkit-options.d/www.facebook.com.conf », qui appartient aussi au paquet account-plugin-facebook 0.12+16.04.20160126-0ubuntu1
InstallationDate: Installed on 2016-07-26 (6 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1.1
 apt 1.2.12~ubuntu16.04.1
SourcePackage: kaccounts-providers
Title: package kaccounts-providers (not installed) failed to install/upgrade: tentative de remplacement de « /etc/signon-ui/webkit-options.d/www.facebook.com.conf », qui appartient aussi au paquet account-plugin-facebook 0.12+16.04.20160126-0ubuntu1
UpgradeStatus: No upgrade log present (probably fresh install)