pip 19.3 breaking on CircleCI `sys.exit(main()) TypeError: 'module' object is not callable`

Environment

• pip version: 19.2.3
• Python version: 3.7
• OS: Debian

More env details can be seen on CircleCI: https://circleci.com/gh/mne-tools/mne-python/16276?utm_campaign=vcs-integration-link&utm_medium=referral&utm_source=github-build-link under the heading spin up environment, and the traceback of the fail under the heading get python running

Description

our CircleCI testing environment started failing today when running pip install --user --upgrade, presumably because of a not-clean upgrade from 19.2.3 (which comes in the docker image) to 19.3.

Expected behavior pip install --user --upgrade should work cleanly and not yield TypeError

Output

#!/bin/bash -eo pipefail
pip install --user --upgrade --progress-bar off pip numpy vtk
pip install --user --upgrade --progress-bar off -r requirements.txt
pip install --user --upgrade --progress-bar off ipython sphinx_fontawesome sphinx_bootstrap_theme "https://api.github.com/repos/sphinx-gallery/sphinx-gallery/zipball/master" memory_profiler "https://api.github.com/repos/nipy/PySurfer/zipball/master"

Collecting pip
  Downloading https://files.pythonhosted.org/packages/4a/08/6ca123073af4ebc4c5488a5bc8a010ac57aa39ce4d3c8a931ad504de4185/pip-19.3-py2.py3-none-any.whl (1.4MB)

Collecting numpy
  Downloading https://files.pythonhosted.org/packages/ba/e0/46e2f0540370f2661b044647fa447fef2ecbcc8f7cdb4329ca2feb03fb23/numpy-1.17.2-cp37-cp37m-manylinux1_x86_64.whl (20.3MB)

Collecting vtk
  Downloading https://files.pythonhosted.org/packages/51/d3/48eb121c4375f7cb15f309a597cd1355198900cb9945dfaf593fca06173a/vtk-8.1.2-cp37-cp37m-manylinux1_x86_64.whl (48.9MB)

Installing collected packages: pip, numpy, vtk
Successfully installed numpy-1.17.2 pip-19.3 vtk-8.1.2
WARNING: You are using pip version 19.2.3, however version 19.3 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
Traceback (most recent call last):
  File "/usr/local/bin/pip", line 10, in <module>
    sys.exit(main())
TypeError: 'module' object is not callable
Exited with code 1

[pfmoore]

The --user upgrade won’t have updated /usr/local/bin/pip, which will still expect to see the old version of pip. But the user install takes precedence, so what it sees is the new version.

You should either use python -m pip or use the wrapper script installed by the --user install (not sure where that gets installed, ~/.local/bin maybe?)

[drammock]

thanks @pfmoore. Using python -m pip seems to have fixed it.