Adjust lib and pythonPackages to upstream nixpkgs changes

[hlolli]

Importing python-packages from top-level is now curried 1 more level, to which I'm failing to understand and reproducing in nix repl, https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/interpreters/python/default.nix#L26

Accessing lib from pkgs.stdenv is now throwing warning so I'm changing the template too.

[seppeljordan]

python3 must be {{ python_version }}

[hlolli]

There are still two tests failing:

1. https://bitbucket.org/tarek/flake8 doesn't exist anymore

2. pypi2nix.requirements.IncompatibleRequirements: Cannot combine requirements with different urls <bound method UrlRequirement.url of UrlRequirement(_name='req', _url='https://url.test', _extras=set(), _environment_markers=None, _logger=<pypi2nix.logger.StreamLogger object at 0x7f0a6ea8feb0>)> and <bound method UrlRequirement.url of UrlRequirement(_name='req', _url='https://url.test', _extras=set(), _environment_markers=None, _logger=<pypi2nix.logger.StreamLogger object at 0x7f0a6ea8feb0>)>

https://url.test seems to my eyes to be equal to https://url.test will look into this one...

[seppeljordan]

You will need to fork this repo since the tests fail and I cannot merge the tests unless they are green. sorry

[hlolli]

You will need to fork this repo since the tests fail and I cannot merge the tests unless they are green. sorry

That's what I meant, I'm looking into these test failure. Will update once done.