The test started failing in commit7d7f62e, but this was not detected due to no automatic test environment. The commit changed the cell numbering from "per-column (K,I,J)-ordering" to "per-plane (I,J,K)-ordering". Consequently, the "correct_answer" seized to be correct. This change restores the "correct_answer" in the ordering introduced by commit7d7f62e. While here, adjust style of the DisjointColumn test case for legibility.