$ git clone -n https://src.fedoraproject.org/rpms/rust-portable-atomic0.3.git /var/lib/mock/f39-build-1642965-40223/root/chroot_tmpdir/scmroot/rust-portable-atomic0.3
Cloning into '/var/lib/mock/f39-build-1642965-40223/root/chroot_tmpdir/scmroot/rust-portable-atomic0.3'...
$ git fetch origin a2f392bb87247f0f28bb10ba26b8af5a133eb800:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-portable-atomic0.3
 * [new ref]         a2f392bb87247f0f28bb10ba26b8af5a133eb800 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a2f392b Added the README