Make tests work on Windows

[gnprice]

We've had a report in chat that the tests don't pass on Windows. Two tests fail, either because they're assuming / is the path-separator character or because of a case mismatch that looks like they're assuming the filesystem is case-sensitive.

Python itself works perfectly fine on Windows, so we should have our Python bindings work fine on Windows too, and we should have our tests pass on Windows to reflect that. I'm not sure if the bug here is only in the tests, or if it affects the library itself, but either way it should be fixed.

[ganpa3]

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