Fixed: chroot-installation_stretch_install_gnome_upgrade_to_sid/8

[jenkins at jenkins.debian.net]

See https://jenkins.debian.net/job/chroot-installation_stretch_install_gnome_upgrade_to_sid/8//console or just https://jenkins.debian.net/job/chroot-installation_stretch_install_gnome_upgrade_to_sid/8/ for more information.