$ git clone -n https://src.fedoraproject.org/rpms/rust-fs4.git /var/lib/mock/f42-build-side-1-3585718-46907/root/chroot_tmpdir/scmroot/rust-fs4
Cloning into '/var/lib/mock/f42-build-side-1-3585718-46907/root/chroot_tmpdir/scmroot/rust-fs4'...
$ git fetch origin 670593802a368f82449194bd366a25043848292f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-fs4
 * [new ref]         670593802a368f82449194bd366a25043848292f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6705938 Update to 0.12.0