$ git clone -n https://src.fedoraproject.org/rpms/rust-tokio-tcp.git /var/lib/mock/f41-build-side-1-3134953-39764/root/chroot_tmpdir/scmroot/rust-tokio-tcp
Cloning into '/var/lib/mock/f41-build-side-1-3134953-39764/root/chroot_tmpdir/scmroot/rust-tokio-tcp'...
$ git fetch origin 62ca8b92b37a43024055f9b4e92d9a46fdbef184:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-tokio-tcp
 * [new ref]         62ca8b92b37a43024055f9b4e92d9a46fdbef184 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 62ca8b9 no longer needed