Keep two different versions of requirements.txt file for Python2 and Python3

[kushaldas]

Description

pip-compile creates different output for requirements.txt for Python2 and in Python3. Which in turn creates problems in installing those dependencies in the different versions.

Probable solution

Have two different requirements files for Python2 and Python3, for both dev and tests.

[rmol]

@kushaldas Unaware of this ticket, I went down a different path trying to address this, and environment markers seemed to work. At least they let me keep Python 2 requirements in the file without breaking Python 3 usage, e.g. enum34 and ipaddress.

Are there other problems they don't cover, or might that be a solution?

[kushaldas]

@rmol I will have to re-research tomorrow morning.

[rmol]

@kushaldas I'd still be interested to hear your thoughts about environment markers, but after further investigation it looks like separate requirements files will be easier.