$ git clone -n https://src.fedoraproject.org/rpms/rust-uu_vdir.git /var/lib/mock/f40-build-781146-131428/root/chroot_tmpdir/scmroot/rust-uu_vdir
Cloning into '/var/lib/mock/f40-build-781146-131428/root/chroot_tmpdir/scmroot/rust-uu_vdir'...
$ git fetch origin e971bb834c78fa88bb0323e82a042179ad16c2da:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-uu_vdir
 * [new ref]         e971bb834c78fa88bb0323e82a042179ad16c2da -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e971bb8 Initial package (rhbz#2258211)