Part of reducing dependency on `py`. Also enables upcoming improvements. In cases where there are simpler alternatives (in tests), I used those. What's left are a couple of uses in `_pytest.main` and `_pytest.python` and they only have modest requirements, so all of the featureful code from py is not needed.  | 
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|---|---|---|
| .. | ||
| approx.py | ||
| collect.py | ||
| fixtures.py | ||
| integration.py | ||
| metafunc.py | ||
| raises.py | ||
| show_fixtures_per_test.py | ||