pip 10 breaks setup

[gsarma]

Internal APIs are no longer exposed so we need to find a work around.
qwigo/warrant#96

[gsarma]

Also, apparently dependency links processing has been deprecated and will eventually be removed. Seems like a can of big can of worms unfortunately:
pypa/pip#4187
pypa/pip#4175
https://www.python.org/dev/peps/pep-0508/

[gsarma]

See https://github.com/gsarma/tests/tree/pip10_workaround for a temporary fix