$ git clone -n https://src.fedoraproject.org/rpms/rust-uu_dir.git /var/lib/mock/f40-build-781136-131424/root/chroot_tmpdir/scmroot/rust-uu_dir
Cloning into '/var/lib/mock/f40-build-781136-131424/root/chroot_tmpdir/scmroot/rust-uu_dir'...
$ git fetch origin 68d2bb97a51d12dfe6906e4242b4f8fddb0418d7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-uu_dir
 * [new ref]         68d2bb97a51d12dfe6906e4242b4f8fddb0418d7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 68d2bb9 Initial package (rhbz#2257493)