Audit sets/dicts of `py.path.local`s

[bluetech]

py.path.local has a footgun flaw: __eq__ on Windows is case-insensitive, but __hash__ returns the hash of the strpath directly, meaning a == b does not imply hash(a) == hash(b). So things like this are possible:

import sys, py
assert sys.platform == "win32"

a = py.path.local("/some/path")
b = py.path.local("/some/PATH")
assert a == b  # Passes
assert a in {b}  # Fails
assert a in {b: 'b'}  # Fails

This probably causes some subtle bugs in pytest, which uses several dicts & sets of py.path.locals. Since py is frozen, it's not possible to fix there.

I haven't checked it yet, but wanted to make a note for later.

[nicoddemus]

Oh my!

py is not really frozen, it is in a "maintenance mode but only for critical bugs", and this qualifies as a critical bug IMHO.

Just to leave this option here in case it was not clear it was an option.

[bluetech]

OK, fixing at the source is definitely best. Sent a PR to py: pytest-dev/py#243

If it gets merged and released, we should probably bump the py requirement in pytest to resolve this issue.

[nicoddemus]

1.8.2 was just released with your fix, thanks!

[bluetech]

Thanks for doing the release @nicoddemus. I sent #7372 to bump the requirement.