$ git clone -n https://src.fedoraproject.org/rpms/Cython.git /var/lib/mock/f40-build-790812-136853/root/chroot_tmpdir/scmroot/Cython
Cloning into '/var/lib/mock/f40-build-790812-136853/root/chroot_tmpdir/scmroot/Cython'...
$ git fetch origin 642a7aa4e119b50c6e263f0b843b22da63120dbd:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/Cython
 * [new ref]         642a7aa4e119b50c6e263f0b843b22da63120dbd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 642a7aa Update to 3.0.8 (rhbz#2255460)