Fix non-ASCII support for prettytoml

[frostming]

Thank you for contributing to Pipenv!

The issue

Fix #2737 Prettytoml doens't support non-ASCII characters well.

The fix

Since the upstream doesn't seem to be maintained anymore, I create a patch for prettytoml. The fix works well on my machine(3.7, Windows/WSL)

The checklist

• Associated issue
• A news fragment in the news/ directory to describe this fix with the extension .bugfix, .feature, .behavior, .doc. .vendor. or .trivial (this will appear in the release changelog). Use semantic line breaks and name the file after the issue number or the PR #.

[frostming]

Python2.7 is still not working when non-ASCII character exists in package name/path or virtualenv location. But I am not going to fix it in this PR. There are other issues tracking unicode support in Python 2.

[techalchemy]

I have a different PR (I think me and @uranusjr are both working on seeing about switching to tomlkit) but would want to see if you can review, no idea if it will even work yet though

[frostming]

That's good, I will take a look into that library.

[techalchemy]

we should put in a good testing framework like hypothesis for cases like this, I'm using that over in vistir for path encodings:

https://github.com/sarugaku/vistir/blob/master/tests/strategies.py#L92

@given(legal_path_chars(), legal_path_chars())
@settings(suppress_health_check=(HealthCheck.filter_too_much,))
def test_mkdir_p(base_dir, subdir):
    assume(not any((dir_name in ["", ".", "./", ".."] for dir_name in [base_dir, subdir])))
    assume(not (os.path.relpath(subdir, start=base_dir) == "."))
    assume(os.path.abspath(base_dir) != os.path.abspath(os.path.join(base_dir, subdir)))
    with vistir.compat.TemporaryDirectory() as temp_dir:
        target = os.path.join(temp_dir.name, base_dir, subdir)
        assume(vistir.path.abspathu(target) != vistir.path.abspathu(os.path.join(temp_dir.name, base_dir)))
        target = vistir.misc.to_bytes(target, encoding="utf-8")
        vistir.path.mkdir_p(target)
        assert os.path.exists(target)

[techalchemy]

I have no clue why this fixes anything but uh, i'll take it. Thank you for sorting this out, it could be a long time before we sort the issues with tomlkit out the rest of teh way.

@uranusjr, any reservations?