$ git clone -n https://src.fedoraproject.org/rpms/mupdf.git /var/lib/mock/f42-build-side-1-3583555-46889/root/chroot_tmpdir/scmroot/mupdf
Cloning into '/var/lib/mock/f42-build-side-1-3583555-46889/root/chroot_tmpdir/scmroot/mupdf'...
$ git fetch origin 2799d802a6984bd9d30d3fb3a3807ddeb50ab159:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mupdf
 * [new ref]         2799d802a6984bd9d30d3fb3a3807ddeb50ab159 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2799d80 Be more helpful with the new font warning