$ git clone -n https://src.fedoraproject.org/rpms/rust-tokio-threadpool.git /var/lib/mock/f41-build-side-1-2897317-34638/root/chroot_tmpdir/scmroot/rust-tokio-threadpool
Cloning into '/var/lib/mock/f41-build-side-1-2897317-34638/root/chroot_tmpdir/scmroot/rust-tokio-threadpool'...
$ git fetch origin 31b7fb6480300f7203eaead905ab43362eeb913b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-tokio-threadpool
 * [new ref]         31b7fb6480300f7203eaead905ab43362eeb913b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 31b7fb6 no longer needed