support version of python in the requirements file

[benoitc]

It would be interesting to have be able to manage a requirement depending on the python version. something like:

futures python < 3.2 
other>=3 python >= 3
other==2 python < 3

So some dependencies or version of them can be installed depending on the version of Python.

[pnasrat]

This could be done via environment markers http://www.python.org/dev/peps/pep-0426/#environment-markers http://www.python.org/dev/peps/pep-0345/#environment-markers

[benoitc]

@pnasrat not sure how it will help here. Can you ellaborate?

The thing I would like to have is a way to handle multiple version depending on the python version in one requirements.txt .

[piotr-dobrogost]

See issue #1433

[qwcode]

closing as dupe to #1433, #1472