With a minimal backport of this test suite to develop@4d4072b3316ac775571ac7d69705bbcf5e9acf96 regression_gh82_test fails, as expected, but every other unit test here passes.  I would argue against their inclusion unless they demonstrate an actual deterministic problem that they're testing.   Also there are commented tests and million-column-wide lines that it'd be awesome to clean up (deleting the former, pretty-printing and commenting the latter).