See #1732 for details, but summarized the CI uses a local path which
differs from the normal remote URL which causes tar_scm service to
complain and no re-create the obscpio. See
openSUSE/obs-service-tar_scm@44b3bee for the relevant change.
Instead of performing a slim rpm build and check directly inside the
container a proper build is performed using `osc build`. The target
package is checked out the _service file pointed at the local copy
and then `osc service disabledrun` before building.