Add support for new environment marker usages

[uranusjr]

Ref pypa/pipenv#1229.

Setuptools added a new syntax in 36.2.1 for conditional requirements. This is recommended in the documentation, and works better with dependency resolution tools that do not actually install the package.

I’m having trouble deciding whether this should be a bugfix or feature. Any suggestions?

---

• Add a new news fragment into the changelog folder
  • name it $issue_id.$type for example (588.bugfix)
  • if you don't have an issue_id change it to the pr id after creating the pr
  • ensure type is one of removal, feature, bugfix, vendor, doc or trivial
  • Make sure to use full sentences with correct case and punctuation, for example: "Fix issue with non-ascii contents in doctest text files."
• Target: for bugfix, vendor, doc or trivial fixes, target master; for removals or features target features;
• Make sure to include reasonable tests for your change if necessary

Unless your change is a trivial or a documentation fix (e.g., a typo or reword of a small section) please:

• Add yourself to AUTHORS, in alphabetical order;

[coveralls]

Coverage remained the same at 92.565% when pulling 9923b51 on uranusjr:pep426-setuptools-36.2.1 into 794fb19 on pytest-dev:master.

[coveralls]

Coverage remained the same at 92.565% when pulling 9923b51 on uranusjr:pep426-setuptools-36.2.1 into 794fb19 on pytest-dev:master.

[nicoddemus]

LGTM, but I will defer to @RonnyPfannschmidt because he's more knowledgeable about setuptools than I am. 😁

[RonnyPfannschmidt]

it looks lgtm, but based on the surrounding changelog the version used is incorrect

based on the change log it was introduced in v36.2.0, incorrect in .1 and fixed in .2 - so the presumed support should start at 36.2.2

[uranusjr]

Changed the version to 36.2.2, and added a link to the change log. I also fixed the other link to change log since it’s broken.

[RonnyPfannschmidt]

lovely, i'll wait for the ci to pass then i'll merge

good job 👍

[coveralls]

Coverage remained the same at 92.565% when pulling b256cd2 on uranusjr:pep426-setuptools-36.2.1 into 794fb19 on pytest-dev:master.

[coveralls]

Coverage remained the same at 92.565% when pulling b256cd2 on uranusjr:pep426-setuptools-36.2.1 into 794fb19 on pytest-dev:master.

[RonnyPfannschmidt]

merged, the failures are unrelated

thanks gain 👍