Steps to reproduce.
* I have host stretch amd64 (let's call it A). I run:
$ sudo cdebootstrap -f minimal stretch /tmp/target http://deb.debian.org/debian # Here I created system B
$ sudo chroot /tmp/target apt-get update
$ sudo chroot /tmp/target apt-get install cdebootstrap
$ sudo chroot /tmp/target cdebootstrap -f minimal stretch /tmp/target http://deb.debian.org/debian # Here I try to create system C
* And I got "E: Failed to re-mount /: Invalid argument"

Here is full log: http://paste.debian.net/996232

If I try to mount /proc, /dev, /dev/pts and /sys (and create symlink /etc/mtab -> /proc/mounts), it still doesn't work.

If I use systemd-nspawn instead of chroot, it works.

This bug report is sent from system B running in systemd-nspawn.