$ git clone -n https://src.fedoraproject.org/rpms/mod_auth_mellon.git /var/lib/mock/f40-build-794740-139784/root/chroot_tmpdir/scmroot/mod_auth_mellon
Cloning into '/var/lib/mock/f40-build-794740-139784/root/chroot_tmpdir/scmroot/mod_auth_mellon'...
$ git fetch origin b37f8f3110dbf084cab0377d43da54cbcf6994a9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mod_auth_mellon
 * [new ref]         b37f8f3110dbf084cab0377d43da54cbcf6994a9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b37f8f3 Rebase to version 0.19.0