$ git clone -n https://src.fedoraproject.org/rpms/racket.git /var/lib/mock/f39-build-1446461-32687/root/chroot_tmpdir/scmroot/racket
Cloning into '/var/lib/mock/f39-build-1446461-32687/root/chroot_tmpdir/scmroot/racket'...
$ git fetch origin 29976eee2d7ea8af10aa0a3e5f37dea42dbf0174:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/racket
 * [new ref]         29976eee2d7ea8af10aa0a3e5f37dea42dbf0174 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 29976ee update to 7.9