Ouch, have the tests for unit-test.arc been failing for the past year? :( :( Very sorry about that. I see the failure now.
I somehow forgot that unit-test.arc has its own tests. Could you post the instructions for running the tests in the Readme? That would also have the salubrious side effect of showing people a way to run a bunch of existing tests.
Once that last one is passing (or maybe even before it's passing), should the top-level tests.arc run these tests too? That way this can be caught not only by Travis CI, but also by people running tests.arc according to the readme.
Anarki isn't really intended to avoid or minimize breaking changes. The unit tests verify only that everything is internally consistent. That boundary around 'internal' should include unit-test.arc, I think.