It's good in tests to use `assert "expected" == actual()`, so why is
pylint all up in my grill about it?

I guess the original line was wrong, but it would have been nice for
unittest2pytest to fix it for me:
https://github.com/pytest-dev/unittest2pytest/issues/52

Bare "assert" statements don't produce the same assertion message as
self.assertEqual did: they don't include the two values compared.  For
some of our own asserts, add back the detailed message.  For some checks
of asserts, it's fine that the values are missing because the longer
messsage includes the information.

unittest2pytest created syntax errors, reported here:
https://github.com/pytest-dev/unittest2pytest/issues/51

This commit fixes them back.

One step of moving to pure pytest tests.

Since we've added a feature (combine --keep).