I wish to make a VM with ‘guix system vm gnu/tests/version-control.scm’,
but it's not working.  It also doesn't work for ‘gnu/tests/web.scm’ and
‘gnu/tests/rsync.scm’.  But I sure it worked with ‘gnu/tests/rsync.scm’.

--8<---------------cut here---------------start------------->8---
$ ./pre-inst-env guix system vm gnu/tests/web.scm
Backtrace:
           5 (primitive-load "/gnu/store/zh0lb2g15hirq7zw2477w7s5ww7dxkv0-guix-0.…")
In guix/ui.scm:
  1375:12  4 (run-guix-command _ . _)
In ice-9/boot-9.scm:
    837:9  3 (catch _ _ #<procedure 7fb95f8569d8 at guix/ui.scm:451:2 (key c)> _)
    837:9  2 (catch _ _ #<procedure 7fb95f8569f0 at guix/ui.scm:539:6 (key proc …> …)
In guix/scripts/system.scm:
   1034:8  1 (_)
   904:28  0 (process-action vm _ ((argument . "gnu/tests/web.scm") (action . #) …))

guix/scripts/system.scm:904:28: In procedure process-action:
guix/scripts/system.scm:904:28: In procedure struct_vtable: Wrong type argument in position 1 (expecting struct): #<unspecified>
--8<---------------cut here---------------end--------------->8---

Then I prepared a VM declaration in system-cgit.scm.  It works and I got
response 200.  So, I have no idea why test fails.