Comment 2 for bug 819427

I've pushed a quick stab at this - it doesnt run the setup/teardown of parent directories at the moment. I wasnt sure how best to test the teardown, hence running the same test twice (a/b). Mr Foord might have a suggestion here.

I should really set the patch of the 'anchor' file absolutely, but __file__ isnt available in the tests for some reason.