$ git clone -n https://src.fedoraproject.org/rpms/rpkg.git /var/lib/mock/f42-build-side-1-3583063-46887/root/chroot_tmpdir/scmroot/rpkg
Cloning into '/var/lib/mock/f42-build-side-1-3583063-46887/root/chroot_tmpdir/scmroot/rpkg'...
$ git fetch origin d0af5cf8ae426249817129414a5962beeb7d31fc:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rpkg
 * [new ref]         d0af5cf8ae426249817129414a5962beeb7d31fc -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d0af5cf Switch to %pyproject_* macros for Fedora releases