$ git clone -n https://src.fedoraproject.org/rpms/muffin.git /var/lib/mock/f39-build-1460253-33195/root/chroot_tmpdir/scmroot/muffin
Cloning into '/var/lib/mock/f39-build-1460253-33195/root/chroot_tmpdir/scmroot/muffin'...
$ git fetch origin a680bd77aa48016624b2ae797878313e3543ed64:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/muffin
 * [new ref]         a680bd77aa48016624b2ae797878313e3543ed64 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a680bd7 fix