/usr/share/zsh/vendor-completions/ is in systemd 215-17+deb8u7.
This file is owned by root:root, with mode 0o755.
..
/usr/share/zsh/vendor-completions/_hostnamectl
/usr/share/zsh/vendor-completions/_journalctl
/usr/share/zsh/vendor-completions/_localectl
/usr/share/zsh/vendor-completions/_loginctl
/usr/share/zsh/vendor-completions/_machinectl
/usr/share/zsh/vendor-completions/_sd_hosts_or_user_at_host
/usr/share/zsh/vendor-completions/_sd_machines
/usr/share/zsh/vendor-completions/_systemctl
/usr/share/zsh/vendor-completions/_systemd
/usr/share/zsh/vendor-completions/_systemd-analyze
/usr/share/zsh/vendor-completions/_systemd-delta
/usr/share/zsh/vendor-completions/_systemd-inhibit
/usr/share/zsh/vendor-completions/_systemd-nspawn
/usr/share/zsh/vendor-completions/_systemd-run
/usr/share/zsh/vendor-completions/_systemd-tmpfiles
/usr/share/zsh/vendor-completions/_timedatectl
/usr/share/zsh/vendor-completions/_udevadm