[bug#29100] [PATCH 2/3] install: Use overlayfs instead of unionfs.

[Danny Milosavljevic]

[...]
> -      (let ((rw-dir (string-append target #$%backing-directory)))
> +      (let* ((rw-dir (string-append target #$%backing-directory))
> +             ;; FIXME: calculate work-dir from backing-directory:
> +             ;; normpath(backing-directory + "../.overlayfs-workdir")
> +             (work-dir (string-append target "/tmp/.overlayfs-workdir")))

What about the FIXME?