MAINT: Fix wheel build to ensure futures is only required in Python 2

[effigies]

Summary

conda create -y -n test python=3.6
source activate test
pip install nipype==1.1.1
pip show futures

Output:

Name: futures
Version: 3.1.1
Summary: Backport of the concurrent.futures package from Python 3.2
Home-page: https://github.com/agronholm/pythonfutures
Author: Brian Quinlan
Author-email: brian@sweetapp.com
License: PSF
Location: /anaconda3/envs/test/lib/python3.6/site-packages
Requires: 
Required-by: nipype

This PR will attempt to ensure the wheel is correctly created to only install futures in Python 2. My suspicion is that upgrading setuptools before building the wheel is the correct fix.

I suggest that we add a hot-fix release, so that downstream Python 3 packages can stop installing futures ASAP.

List of changes proposed in this PR (pull-request)

Acknowledgment

• (Mandatory) I acknowledge that this contribution will be available under the Apache 2 license.

[effigies]

That resolved it:

$ grep futures nipype-1.1.*/*
nipype-1.1.1.dist-info/METADATA:Requires-Dist: futures
nipype-1.1.2.dev0+g8f744ec33.dist-info/METADATA:Requires-Dist: futures; python_version == "2.7"
nipype-1.1.2.dev0+gae913a2b2.dist-info/METADATA:Requires-Dist: futures

And pip installing nipype-1.1.2.dev0+g8f744ec33-py2.py3-none-any.whl installs futures on Python 2, but not Python 3.

I need to update the tag build, but I'm going to see if I can add some install tests to the PyPI test so we can be sure this doesn't crop back up.

[effigies]

Okay, ready for review. @mgxd @satra How do you feel about a hotfix? And should we do it off of master (with some post-1.1.1 changes already in), or just these changes on top of 1.1.1?

[mgxd]

LGTM, i'm fine with releasing 1.1.2 a little early to get this fix out

[mgxd]

is this running on every build or just tagged ones?

[effigies]

Every build. The idea is to get an error before we tag and have to re-tag. I was only doing it on rel/* branches, but it's a 2min job.

[mgxd]

I like doing it on rel/ branches since we'll tag after those pass - but 2 mins is not the end of the world for me

[effigies]

I'll move it back in the rel branch.

[effigies]

Do we want to do 1.1.3 at the end of the month, the end of next month, or shoot for a month from 1.1.2?

[mgxd]

i vote targeting end of next

[effigies]

Sounds good. Created milestone 1.1.3 and moved everything else there. I'll merge on pass and start a rel/1.1.2 branch.

[satra]

@effigies - hotfix is good to release.