$ git clone -n https://src.fedoraproject.org/rpms/racket.git /var/lib/mock/f42-build-side-1-3584129-46891/root/chroot_tmpdir/scmroot/racket
Cloning into '/var/lib/mock/f42-build-side-1-3584129-46891/root/chroot_tmpdir/scmroot/racket'...
$ git fetch origin e0f1ae8da2dd42eebce477b0235f5456ac0ca487:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/racket
 * [new ref]         e0f1ae8da2dd42eebce477b0235f5456ac0ca487 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e0f1ae8 update to 8.17