Fix setup.py to work with setuptools 41.4.0 and later

[generalmimon]

I haven't tested it, but looking at the setup.py file in this repo concerns me, if here couldn't happen the same problem with setuptools>=41.4.0 as we encountered in the kaitai_struct_python_runtime repo (kaitai-io/kaitai_struct_python_runtime#46).

In this comment kaitai-io/kaitai_struct_python_runtime#43 (comment) in the issue reporting the problem, @dgelessus wrote this:

This error is caused by setup.py files trying to read setup.cfg manually, which is not officially supported (see pypa/setuptools#1869). You're supposed to just call setup() without arguments and let setuptools find and read the setup.cfg file itself.

If that was the case, I think the same can happen also in this repo. Here's the setup.py here:

kaitai_fs/setup.py

Lines 7 to 11 in 0c4a773

	cfg = read_configuration(str(Path(__file__).parent / 'setup.cfg'))
	#print(cfg)
	cfg["options"].update(cfg["metadata"])
	cfg = cfg["options"]
	setup(**cfg)

I don't have any deep experience with setuptools, setup.py and this kind of stuff, but this seems to me a lot like setup.py files trying to read setup.cfg manually.

@dgelessus, could you please look at it and possibly fix it?

[dgelessus]

Just tested - python3 -m pip install ./kaitai_fs actually works without issues with pip==20.1.1 and setuptools==47.3.1 (which are the latest versions currently).

The error that we had with kaitai_struct_python_runtime only happens when you read setup.cfg manually and the setup.cfg has a python_requires setting in the [options] section. kaitai_fs's setup.cfg doesn't use python_requires, so the error doesn't occur here.

You are right though that the setup.py here is manually reading/parsing setup.cfg, which is not supported (even though it doesn't give any errors here), so we should fix that. I'll make a PR.

[generalmimon]

@dgelessus Thanks for your review and the clarification, at least I'm a little wiser 🙂