Noticed that there is no >= etc. in the environment markers spec, but both environment markers implementations allow it. Shall I fix the spec?

As of wheel 0.9.5, you can add to your setup.cfg lines to be included as Requires-Dist: in the output METADATA. They supplement setup.py's values. Only problem is they are only resolved during install from wheel, and not during an install directly from the sdist.

[metadata] requires_dist = beaglevote; python_version == 2.7 reportlab quux; sys.platform == 'win32'