ERROR: Could not find a version that satisfies the requirement black==20.8b1

[gmjonker]

Versions:
Pants 2.4.1rc1, 2.4.0
Python 3.7

Problem:
On MacOS, after checking out the repo and running ./pants lint ::, I get the following error:

❯ ~/repos/pants-example main ./pants lint ::
22:33:11.40 [INFO] Completed: Building isort.pex with 2 requirements: isort[pyproject]>=5.5.1,<5.6, setuptools
22:33:11.53 [INFO] Completed: Building docformatter.pex with 1 requirement: docformatter>=1.3.1,<1.4
22:33:11.83 [INFO] Completed: lint - Docformatter succeeded.
22:33:11.93 [INFO] Completed: lint - isort succeeded.
22:33:12.16 [INFO] Completed: Building flake8.pex with 3 requirements: flake8>=3.7.9,<3.9, setuptools; python_version > '2.7', setuptools<45; python_full_version == '2.7.*'
22:33:12.69 [INFO] Completed: lint - Flake8 succeeded.
22:33:16.04 [INFO] Completed: Building black.pex with 2 requirements: black==20.8b1, setuptools
22:33:16.04 [ERROR] Exception caught: (pants.engine.internals.scheduler.ExecutionError)
  File "/Users/geert/.cache/pants/setup/bootstrap-Darwin-x86_64/2.4.1rc1_py37/lib/python3.7/site-packages/pants/bin/local_pants_runner.py", line 229, in _run_inner
    return self._perform_run(goals)
  File "/Users/geert/.cache/pants/setup/bootstrap-Darwin-x86_64/2.4.1rc1_py37/lib/python3.7/site-packages/pants/bin/local_pants_runner.py", line 168, in _perform_run
    return self._perform_run_body(goals, poll=False)
  File "/Users/geert/.cache/pants/setup/bootstrap-Darwin-x86_64/2.4.1rc1_py37/lib/python3.7/site-packages/pants/bin/local_pants_runner.py", line 190, in _perform_run_body
    poll_delay=(0.1 if poll else None),
  File "/Users/geert/.cache/pants/setup/bootstrap-Darwin-x86_64/2.4.1rc1_py37/lib/python3.7/site-packages/pants/init/engine_initializer.py", line 136, in run_goal_rules
    goal_product, params, poll=poll, poll_delay=poll_delay
  File "/Users/geert/.cache/pants/setup/bootstrap-Darwin-x86_64/2.4.1rc1_py37/lib/python3.7/site-packages/pants/engine/internals/scheduler.py", line 530, in run_goal_rule
    self._raise_on_error([t for _, t in throws])
  File "/Users/geert/.cache/pants/setup/bootstrap-Darwin-x86_64/2.4.1rc1_py37/lib/python3.7/site-packages/pants/engine/internals/scheduler.py", line 500, in _raise_on_error
    wrapped_exceptions=tuple(t.exc for t in throws),

Exception message: 1 Exception encountered:

  ProcessExecutionFailure: Process 'Building black.pex with 2 requirements: black==20.8b1, setuptools' failed with exit code 1.
stdout:

stderr:
WARNING: Discarding https://files.pythonhosted.org/packages/dc/7b/5a6bbe89de849f28d7c109f5ea87b65afa5124ad615f3419e71beb29dc96/black-20.8b1.tar.gz#sha256=1c02557aa099101b9d21496f8a914e9ed2222ef70336404eeeac8edba836fbea (from https://pypi.org/simple/black/) (requires-python:>=3.6). Command errored out with exit status 1: /Library/Developer/CommandLineTools/usr/bin/python3 /Users/geert/.cache/pants/named_caches/pex_root/pip.pex/cf4106b4c7898b462f7c172dde686a9747103f1a/.deps/pip/pip install --ignore-installed --no-user --prefix /private/var/folders/9b/ljk7fx753j16dyrbpwz_l1gh0000gn/T/process-executionFJIqxu/.tmp/pip-build-env-cf_if63x/overlay --no-warn-script-location -v --no-binary :none: --only-binary :none: -i https://pypi.org/simple/ -- 'setuptools>=41.0' setuptools-scm wheel Check the logs for full command output.
ERROR: Could not find a version that satisfies the requirement black==20.8b1
ERROR: No matching distribution found for black==20.8b1
pid 80715 -> /usr/bin/python3 /Users/geert/.cache/pants/named_caches/pex_root/pip.pex/cf4106b4c7898b462f7c172dde686a9747103f1a --disable-pip-version-check --no-python-version-warning --exists-action a --isolated -q --cache-dir /Users/geert/.cache/pants/named_caches/pex_root --log /private/var/folders/9b/ljk7fx753j16dyrbpwz_l1gh0000gn/T/process-executionFJIqxu/.tmp/tmpnd0f6vzy/pip.log download --dest /private/var/folders/9b/ljk7fx753j16dyrbpwz_l1gh0000gn/T/process-executionFJIqxu/.tmp/tmpyw40260n/usr.bin.python3 --constraint constraints.txt black==20.8b1 setuptools --index-url https://pypi.org/simple/ --retries 5 --timeout 15 exited with 1 and STDERR:
None

(Use --print-stacktrace to see more error details.)

[benjyw]

Thanks for the report. That is strange. I can't reproduce. What happens if you pip install black==20.8b1 setuptools in a virtualenv?

[gmjonker]

That works fine

[benjyw]

Hmm, trying to think how to debug this. Is this system python, brew python or pyenv python?

[gmjonker]

I think I used the official Python installer

❯ ~/repos/pants-example main* which python3.7
/Library/Frameworks/Python.framework/Versions/3.7/bin/python3.7

[benjyw]

There are various known problems with the system Pythons on OSX. If it's not too much trouble could you try brew-installing a python interpreter, or using pyenv to install one?

[gmjonker]

Installed python 3.9.5 with brew and now it's working!

[benjyw]

Great! Glad to hear it.

MacOS system pythons are unfortunately problematic in various ways.