Fix setup.py requirements parsing with Pip 20+

[WinterPhoenix]

Accidentally removed the old repo tied to this Pull Request, so I'm resubmitting.

Original PR here: #19

[coveralls]

Coverage increased (+0.1%) to 90.506% when pulling 18bb08d on WinterPhoenix:patch-1 into 3b03ec3 on leovp:master.

[sakshatshinde]

Has this not been merged yet?

[pgh268400]

I think this pr should be merged. In latest version of pip

The package is not installed properly because of the import statement below.

try: # for pip >= 10
from pip._internal.req import parse_requirements
from pip._internal.download import PipSession
except ImportError: # for pip <= 9.0.3
from pip.req import parse_requirements
from pip.download import PipSession

The package was installed properly only after manually downloading the library and manually applying the pr to setup.py.

However, after finishing installing the package, I encountered this error.

[sakshatshinde]

Any update? @leovp @NullSoldier