Wow, this works: (type "bind") (flags '(bind-mount)) and it works by *not* putting any entry in /etc/fstab, yet doing the thing somehow. So the bug in mount is still there, but is worked around.
> https://guix.gnu.org/manual/en/html_node/File-Systems.html Indeed bind-mount is mentioned there, but vastly under-documented, especially since the guix paragraph refers to some glibc documentation for mount(2) for details, and those details saying nothing whatsoever about bind.
