$ git clone -n https://src.fedoraproject.org/rpms/rust-futures-io.git /var/lib/mock/f39-build-2165747-50984/root/chroot_tmpdir/scmroot/rust-futures-io
Cloning into '/var/lib/mock/f39-build-2165747-50984/root/chroot_tmpdir/scmroot/rust-futures-io'...
$ git fetch origin 3800ec225694c7b5dc8874ddf46bedd30d5733d2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-futures-io
 * [new ref]         3800ec225694c7b5dc8874ddf46bedd30d5733d2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3800ec2 Update to version 0.3.30; Fixes RHBZ#2246392