1. You end up either inverting the sense of a `coverage_conditional_plugin`
pragma's name (versus what it actually tests), *or* where you put it in
the code.
2. As the pragmas are only defined in once, in one place, it's better to
invert the sense there, rather than in *every single use case*.
Then technically any 'other' branch isn't guaranteed to
* Define `darwin` and `linux` *and* "platform known" pragmas.
* Use per-platform pragmas in `config/__init__.py` selection of implementation.
* Attempt, and fail, to use pragma in `config/darwin.py` to ignore it on
other platforms.
* Always report on coverage, if no tests failed.
* Remove `.coveragerc`, in favour of `pyproject.toml`.
* Use `coverage-conditional-plugin`:
- Two rules added, `sys-platform-win32` and `sys-platform-not-win32`.
- Those rules used so non-win32 code run on win32 doesn't cause coverage
to be reported as less than 100%.
There's the assumption that !win32 means Linux, probably.
