$ git clone -n https://src.fedoraproject.org/rpms/rust-ff.git /var/lib/mock/f38-build-side-43-rust-devel-1418564-31459/root/chroot_tmpdir/scmroot/rust-ff
Cloning into '/var/lib/mock/f38-build-side-43-rust-devel-1418564-31459/root/chroot_tmpdir/scmroot/rust-ff'...
$ git fetch origin 8add21ffac6447ee40933452e7d5ddfcc1a456b3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-ff
 * [new ref]         8add21ffac6447ee40933452e7d5ddfcc1a456b3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8add21f Initial import (#2211920)