$ git clone -n https://src.fedoraproject.org/rpms/rust-keccak.git /var/lib/mock/f45-build-42731-796/root/chroot_tmpdir/scmroot/rust-keccak
Cloning into '/var/lib/mock/f45-build-42731-796/root/chroot_tmpdir/scmroot/rust-keccak'...
$ git fetch origin fa2a6c522aa6f35bf7950fa2d015d7949f5e28d2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-keccak
 * [new ref]         fa2a6c522aa6f35bf7950fa2d015d7949f5e28d2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at fa2a6c5 Update to version 0.2.2; Fixes RHBZ#2447837