Installing futures backport on Python 2 breaks pipenv on Python 3

The problem appears on systems with Python 2 installed as a default (unfortunately, will still be around for at least several years!) and pipenv installed on Python 2 accordingly, when users are trying to create and manage Python 3 virtualenvs.

See details about my specific setup here:

https://github.com/pypa/pipenv/issues/1686#issuecomment-373019016

---

Expected result

pipenv works.

Actual result

pipenv bails out with an exception:

zaytsev@work:~/src/pipenv$ docker run -it --rm pipenv-bug
port Link
  File "/root/.local/lib/python2.7/site-packages/pipenv/../pipenv/vendor/pip9/index.py", line 31, in <module>
    from pip9.wheel import Wheel, wheel_ext
  File "/root/.local/lib/python2.7/site-packages/pipenv/../pipenv/vendor/pip9/wheel.py", line 6, in <module>
    import compileall
  File "/usr/lib/python3.6/compileall.py", line 20, in <module>
    from concurrent.futures import ProcessPoolExecutor
  File "/root/.local/lib/python2.7/site-packages/pipenv/../pipenv/../concurrent/futures/__init__.py", line 8, in <module>
    from concurrent.futures._base import (FIRST_COMPLETED,
  File "/root/.local/lib/python2.7/site-packages/pipenv/../pipenv/../concurrent/futures/_base.py", line 414
    raise exception_type, self._exception, self._traceback
                        ^
SyntaxError: invalid syntax

Steps to replicate

# Build image
zaytsev@work:~/src/pipenv$ docker build . --tag pipenv-bug

# Reproduce bug
zaytsev@work:~/src/pipenv$ docker run -it --rm pipenv-bug

# Debug live
zaytsev@work:~/src/pipenv$ docker run -it --rm pipenv-bug /bin/sh

Dockerfile:

zaytsev@work:~/src/pipenv$ cat Dockerfile 
FROM python:2.7-alpine3.7

WORKDIR /opt

RUN apk add --no-cache python3 gcc musl-dev libffi-dev openssl-dev

RUN pip install --user pipenv

ENV PATH="/root/.local/bin:${PATH}" SHELL="/bin/sh"

RUN pipenv --python 3.6

# Installing this breaks pipenv!
RUN pip install --user futures

CMD ["pipenv", "update", "--dry-run"]

Duplicates:

• #1686
• #1603
• #1589
• #1553

[zyv]

@kennethreitz I am very disappointed by your reaction. I have really put much time into helping you to isolate, reproduce and debug this issue. I have finally created a working reproducer that you can just run out of the box on any system, so as suggested in the other issue, I’ve opened a new clean issue with detailed explanations on how to reproduce the isolated problem.

Obviously, this is the first step to fixing the issue. If I didn’t want to help you, I would have spared the time I invested so far and went out to get drunk instead of tinkering with Docker…

Whether I will be able to find enough time to submit a pull request, I don’t know. I hope so, but I’m unfamiliar with pipenv code. Now, on top of that, your reaction doesn’t sound welcoming at all, and frankly speaking, I feel demotivated.

[kennethreitz]

If you’d like to help, please try to help fix the problem, instead of continuing to tell us about it in new and creative ways.