$ git clone -n https://src.fedoraproject.org/rpms/csdiff.git /var/lib/mock/f41-build-813506-148684/root/chroot_tmpdir/scmroot/csdiff
Cloning into '/var/lib/mock/f41-build-813506-148684/root/chroot_tmpdir/scmroot/csdiff'...
$ git fetch origin 0eba88a758cb40d3c8774aa83755bf14c22a99a2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/csdiff
 * [new ref]         0eba88a758cb40d3c8774aa83755bf14c22a99a2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0eba88a update to latest upstream (3.4.0)