Bug: circular dependency results in Dependencies.dependencies_exists() = True

[MacHu-GWU]

In this test case, it has a circular dependency. but the test case shows that dependencies_exists, but eventually the dependencies.resolve_dependencies() method not working. is this designed on purpose?

items_1_mistakes = {
    'A': ['B', 'C', 'D'],  # -- A is dependent on B, C, D,
    'B': [],  # -- B is dependent on nothing, etc.
    'C': ['D'],
    'D': ['B', 'E'],
    'E': ['A'],
    'F': [],
    'Z': ['A', 'B', 'C', 'D']
}

deps = Dependencies(items_1_mistakes)
assert deps.dependencies_exist(verbose=False)

https://github.com/jakesherman/dependency_algorithm/blob/master/tests/test_dependency_algorithm.py#L24