Merci pour vos réponses. Voici les infos:
$ apt policy
Fichiers du paquet :
100 /var/lib/dpkg/status
release a=now
500 https://repo.skype.com/deb stable/main amd64 Packages
release o=. stable,a=stable,n=stable,l=. stable,c=main,b=amd64
origin repo.skype.com
500 http://lazka.github.io/ql-debian/stable quodlibet-stable/ Packages
release o=lazka,a=quodlibet-stable,n=quodlibet-stable,l=lazka,c=
origin lazka.github.io
100 http://ftp.fr.debian.org/debian stretch-backports/non-free i386 Packages
release o=Debian Backports,a=stretch-backports,n=stretch-backports,l=Debian Backports,c=non-free,b=i386
origin ftp.fr.debian.org
100 http://ftp.fr.debian.org/debian stretch-backports/non-free amd64 Packages
release o=Debian Backports,a=stretch-backports,n=stretch-backports,l=Debian Backports,c=non-free,b=amd64
origin ftp.fr.debian.org
100 http://ftp.fr.debian.org/debian stretch-backports/contrib i386 Packages
release o=Debian Backports,a=stretch-backports,n=stretch-backports,l=Debian Backports,c=contrib,b=i386
origin ftp.fr.debian.org
100 http://ftp.fr.debian.org/debian stretch-backports/contrib amd64 Packages
release o=Debian Backports,a=stretch-backports,n=stretch-backports,l=Debian Backports,c=contrib,b=amd64
origin ftp.fr.debian.org
100 http://ftp.fr.debian.org/debian stretch-backports/main i386 Packages
release o=Debian Backports,a=stretch-backports,n=stretch-backports,l=Debian Backports,c=main,b=i386
origin ftp.fr.debian.org
100 http://ftp.fr.debian.org/debian stretch-backports/main amd64 Packages
release o=Debian Backports,a=stretch-backports,n=stretch-backports,l=Debian Backports,c=main,b=amd64
origin ftp.fr.debian.org
500 http://ftp.fr.debian.org/debian stretch-updates/main i386 Packages
release o=Debian,a=stable-updates,n=stretch-updates,l=Debian,c=main,b=i386
origin ftp.fr.debian.org
500 http://ftp.fr.debian.org/debian stretch-updates/main amd64 Packages
release o=Debian,a=stable-updates,n=stretch-updates,l=Debian,c=main,b=amd64
origin ftp.fr.debian.org
500 http://security.debian.org stretch/updates/non-free i386 Packages
release v=9,o=Debian,a=stable,n=stretch,l=Debian-Security,c=non-free,b=i386
origin security.debian.org
500 http://security.debian.org stretch/updates/non-free amd64 Packages
release v=9,o=Debian,a=stable,n=stretch,l=Debian-Security,c=non-free,b=amd64
origin security.debian.org
500 http://security.debian.org stretch/updates/contrib i386 Packages
release v=9,o=Debian,a=stable,n=stretch,l=Debian-Security,c=contrib,b=i386
origin security.debian.org
500 http://security.debian.org stretch/updates/contrib amd64 Packages
release v=9,o=Debian,a=stable,n=stretch,l=Debian-Security,c=contrib,b=amd64
origin security.debian.org
500 http://security.debian.org stretch/updates/main i386 Packages
release v=9,o=Debian,a=stable,n=stretch,l=Debian-Security,c=main,b=i386
origin security.debian.org
500 http://security.debian.org stretch/updates/main amd64 Packages
release v=9,o=Debian,a=stable,n=stretch,l=Debian-Security,c=main,b=amd64
origin security.debian.org
500 http://ftp.fr.debian.org/debian stretch/non-free i386 Packages
release v=9.6,o=Debian,a=stable,n=stretch,l=Debian,c=non-free,b=i386
origin ftp.fr.debian.org
500 http://ftp.fr.debian.org/debian stretch/non-free amd64 Packages
release v=9.6,o=Debian,a=stable,n=stretch,l=Debian,c=non-free,b=amd64
origin ftp.fr.debian.org
500 http://ftp.fr.debian.org/debian stretch/contrib i386 Packages
release v=9.6,o=Debian,a=stable,n=stretch,l=Debian,c=contrib,b=i386
origin ftp.fr.debian.org
500 http://ftp.fr.debian.org/debian stretch/contrib amd64 Packages
release v=9.6,o=Debian,a=stable,n=stretch,l=Debian,c=contrib,b=amd64
origin ftp.fr.debian.org
500 http://ftp.fr.debian.org/debian stretch/main i386 Packages
release v=9.6,o=Debian,a=stable,n=stretch,l=Debian,c=main,b=i386
origin ftp.fr.debian.org
500 http://ftp.fr.debian.org/debian stretch/main amd64 Packages
release v=9.6,o=Debian,a=stable,n=stretch,l=Debian,c=main,b=amd64
origin ftp.fr.debian.org
600 https://repository.solydxk.com solydxk-9/import i386 Packages
release v=1,o=SolydXK,a=solydxk-9,n=solydxk-9,l=SolydXK,c=import,b=i386
origin repository.solydxk.com
600 https://repository.solydxk.com solydxk-9/import amd64 Packages
release v=1,o=SolydXK,a=solydxk-9,n=solydxk-9,l=SolydXK,c=import,b=amd64
origin repository.solydxk.com
600 https://repository.solydxk.com solydxk-9/main i386 Packages
release v=1,o=SolydXK,a=solydxk-9,n=solydxk-9,l=SolydXK,c=main,b=i386
origin repository.solydxk.com
600 https://repository.solydxk.com solydxk-9/main amd64 Packages
release v=1,o=SolydXK,a=solydxk-9,n=solydxk-9,l=SolydXK,c=main,b=amd64
origin repository.solydxk.com
Paquets épinglés :