As explained in previous commit, real_data tail was ending without \n

    99988,99989\n99990,99991,99992,99993,99994,99995,99996,99997,99998,99999\n100000

and because DataStream_copyCSVToDataArray() processes data in full lines only,
the tail was lost.

Fix t by making sure the last line is always terminated properly with \n.

/cc @Tyagov