Installer Firefox 57 (alias Quantum) sur Debian stable Stretch

echo 'deb http://ftp.fr.debian.org/debian/ unstable main contrib non-free' >> /etc/apt/sources.list
echo 'deb http://ftp.fr.debian.org/debian/ sid main contrib non-free' >> /etc/apt/sources.list
echo 'deb http://ftp.fr.debian.org/debian/ experimental main contrib non-free' >> /etc/apt/sources.list
apt update
aptitude install firefox=57.0~b9-1
head -n -3 /etc/apt/sources.list > /tmp/sources.list
mv /tmp/sources.list /etc/sources.list