futures package being installed in Docker image

[effigies]

Despite nipype indicating that futures should only be installed for Python 2.7 (see nipype/info.py#L151, we see the following in the Docker output:

Collecting futures (from nipype>=1.1.0->niworkflows>=0.4.2->-r requirements.txt (line 1))
  Downloading https://files.pythonhosted.org/packages/cc/26/b61e3a4eb50653e8a7339d84eeaa46d1e93b92951978873c220ae64d0733/futures-3.1.1.tar.gz

I don't see this simply pip installing nipype in a new conda environment locally, but it does occur within the Docker container. Upgrading pip to version 18 doesn't resolve the issue.

While I don't understand why this doesn't seem to cause issues for running fmriprep, it does cause issues for testing in the Docker container. (I also don't understand why it's not causing problems on Circle.)

[oesteban]

Good catch

[effigies]

This is a nipype wheel-building problem, not a misconfiguration on our end. See nipy/nipype#2678.