$ git clone -n https://src.fedoraproject.org/rpms/csdiff.git /var/lib/mock/f42-build-side-1-3583180-46888/root/chroot_tmpdir/scmroot/csdiff
Cloning into '/var/lib/mock/f42-build-side-1-3583180-46888/root/chroot_tmpdir/scmroot/csdiff'...
$ git fetch origin d1092f8c47a4821f26b54da6eef46a6aa4e763f7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/csdiff
 * [new ref]         d1092f8c47a4821f26b54da6eef46a6aa4e763f7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d1092f8 update to latest upstream (3.5.5)