test_multiple_col_ensure.py is stochastic

This failure should not be stochastic because we fixed the seed. But sometimes it fails like this:

=================================== FAILURES ===================================
_________________ test_multiple_col_ensure[130223-False-True] __________________

seed = 130223, dependent = False, analyze = True

@pytest.mark.parametrize("seed, dependent, analyze", single_args)
def test_multiple_col_ensure(seed, dependent, analyze):
    rng = random.Random(seed)
    T, M_r, M_c, X_L, X_D, engine = quick_le(get_next_seed(rng))
    col_pairs = [(c1, c2,) for c1, c2 in it.combinations(range(N_COLS), 2)]
    ensure_pairs = random.sample(col_pairs, 4)
    dep_constraints = [(c1, c2, dependent) for c1, c2 in ensure_pairs]

    X_L, X_D = engine.ensure_col_dep_constraints(M_c, M_r, T, X_L, X_D,
    dep_constraints, get_next_seed(rng))

    for col1, col2, dep in dep_constraints:
    assert engine.assert_col_dep_constraints(X_L, X_D, col1, col2, dep, True)

    if analyze:
    X_L, X_D = engine.analyze(M_c, T, X_L, X_D, get_next_seed(rng),
        n_steps=1000)

    for col1, col2, dep in dep_constraints:
>               assert engine.assert_col_dep_constraints(X_L, X_D, col1, col2, dep, True)
E               assert <bound method LocalEngine.assert_col_dep_constraints of <crosscat.LocalEngine.LocalEngine object at 0x7fc498d4f210>>({'col_ensure': {'dependent': {}, 'independent': {'1': [9], '2': [5], '3': [6], '5': [2], ...}}, 'column_hypers': [{'fi... 'column_names': [5, 6, 7, 8, 9], 'row_partition_model': {'counts': [5, 5], 'hypers': {'alpha': 0.2511886431509581}}}]}, [[0, 1, 1, 0, 0, 0, ...], [0, 1, 1, 1, 1, 0, ...]], 6, 9, False, True)
E                +  where <bound method LocalEngine.assert_col_dep_constraints of <crosscat.LocalEngine.LocalEngine object at 0x7fc498d4f210>> = <crosscat.LocalEngine.LocalEngine object at 0x7fc498d4f210>.assert_col_dep_constraints

src/tests/unit_tests/test_col_ensure.py:123: AssertionError
===Flaky Test Report===