Fixes <https://bugs.gnu.org/36378>.
Reported by Reza Alizadeh Majd <r.majd@pantherx.org>.
* build-aux/hydra/gnu-system.scm (find-current-checkout): New procedure.
(hydra-jobs): Use FIND-CURRENT-CHECKOUT to define CHECKOUT. Pass it to the
inferior Guix as an extra argument whose key is 'superior-guix-checkout'.
* gnu/ci.scm (find-current-checkout): New procedure.
(hydra-jobs): Use FIND-CURRENT-CHECKOUT to define CHECKOUT. This will return
'#f' if the current Guix is an inferior. In that case, use the
'superior-guix-checkout' argument provided by the superior Guix.
f71b0a0012