pre-commit fails when setting up the black environment.

Describe the bug

pre-commit fails when setting up the black environment.

To Reproduce

When using pre-commit with a version of black tagged later than 18.9b0 (including stable or master, the initial setup of the black environment fails with the following output.

[INFO] Installing environment for https://github.com/psf/black.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
An unexpected error has occurred: CalledProcessError: Command: ('/home/rae/.cache/pre-commit/reporrf_4ype/py_env-python3.7/bin/python3.7', '/home/rae/.cache/pre-commit/reporrf_4ype/py_env-python3.7/bin/pip', 'install', '.')
Return code: 1
Expected return code: 0
Output:
    Processing /home/rae/.cache/pre-commit/reporrf_4ype
      Installing build dependencies: started
      Installing build dependencies: finished with status 'done'
      Getting requirements to build wheel: started
      Getting requirements to build wheel: finished with status 'done'
        Preparing wheel metadata: started
        Preparing wheel metadata: finished with status 'error'
   
Errors:
        ERROR: Command errored out with exit status 1:
         command: /home/rae/.cache/pre-commit/reporrf_4ype/py_env-python3.7/bin/python3.7 /home/rae/.cache/pre-commit/reporrf_4ype/py_env-python3.7/lib/python3.7/site-packages/pip/_vendor/pep517/_in_process.py prepare_metadata_for_build_wheel /tmp/tmp7yzty2sc
             cwd: /tmp/pip-req-build-1ksmcb94
        Complete output (36 lines):
        Traceback (most recent call last):
          File "/home/rae/.cache/pre-commit/reporrf_4ype/py_env-python3.7/lib/python3.7/site-packages/pip/_vendor/pep517/_in_process.py", line 257, in <module>
            main()
          File "/home/rae/.cache/pre-commit/reporrf_4ype/py_env-python3.7/lib/python3.7/site-packages/pip/_vendor/pep517/_in_process.py", line 240, in main
            json_out['return_val'] = hook(**hook_input['kwargs'])
          File "/home/rae/.cache/pre-commit/reporrf_4ype/py_env-python3.7/lib/python3.7/site-packages/pip/_vendor/pep517/_in_process.py", line 110, in prepare_metadata_for_build_wheel
            return hook(metadata_directory, config_settings)
          File "/tmp/pip-build-env-2tuvz0xl/overlay/lib/python3.7/site-packages/setuptools/build_meta.py", line 156, in prepare_metadata_for_build_wheel
            self.run_setup()
          File "/tmp/pip-build-env-2tuvz0xl/overlay/lib/python3.7/site-packages/setuptools/build_meta.py", line 142, in run_setup
            exec(compile(code, __file__, 'exec'), locals())
          File "setup.py", line 65, in <module>
            "blackd=blackd:patched_main [d]",
          File "/tmp/pip-build-env-2tuvz0xl/overlay/lib/python3.7/site-packages/setuptools/__init__.py", line 145, in setup
            return distutils.core.setup(**attrs)
          File "/home/rae/.pyenv/versions/3.7.3/lib/python3.7/distutils/core.py", line 108, in setup
            _setup_distribution = dist = klass(attrs)
          File "/tmp/pip-build-env-2tuvz0xl/overlay/lib/python3.7/site-packages/setuptools/dist.py", line 448, in __init__
            k: v for k, v in attrs.items()
          File "/home/rae/.pyenv/versions/3.7.3/lib/python3.7/distutils/dist.py", line 292, in __init__
            self.finalize_options()
          File "/tmp/pip-build-env-2tuvz0xl/overlay/lib/python3.7/site-packages/setuptools/dist.py", line 740, in finalize_options
            ep.load()(self)
          File "/tmp/pip-build-env-2tuvz0xl/overlay/lib/python3.7/site-packages/setuptools/dist.py", line 747, in _finalize_setup_keywords
            ep.load()(self, ep.name, value)
          File "/tmp/pip-build-env-2tuvz0xl/overlay/lib/python3.7/site-packages/setuptools_scm/integration.py", line 17, in version_keyword
            dist.metadata.version = get_version(**value)
          File "/tmp/pip-build-env-2tuvz0xl/overlay/lib/python3.7/site-packages/setuptools_scm/__init__.py", line 150, in get_version
            parsed_version = _do_parse(config)
          File "/tmp/pip-build-env-2tuvz0xl/overlay/lib/python3.7/site-packages/setuptools_scm/__init__.py", line 113, in _do_parse
            "use git+https://github.com/user/proj.git#egg=proj" % config.absolute_root
        LookupError: setuptools-scm was unable to detect version for '/tmp/pip-req-build-1ksmcb94'.
       
        Make sure you're either building from a fully intact git repository or PyPI tarballs. Most other sources (such as GitHub's tarballs, a git checkout without the .git folder) don't contain the necessary metadata and will not work.
       
       For example, if you're using pip, instead of https://github.com/user/proj/archive/master.zip use git+https://github.com/user/proj.git#egg=proj
        ----------------------------------------
    ERROR: Command errored out with exit status 1: /home/rae/.cache/pre-commit/reporrf_4ype/py_env-python3.7/bin/python3.7 /home/rae/.cache/pre-commit/reporrf_4ype/py_env-python3.7/lib/python3.7/site-packages/pip/_vendor/pep517/_in_process.py prepare_metadata_for_build_wheel /tmp/tmp7yzty2sc Check the logs for full command output.
   
Check the log at /home/rae/.cache/pre-commit/pre-commit.log

A longer log, with export SETUPTOOLS_SCM_DEBUG=1, is here: https://pastebin.com/YfYsxPPC.

I noticed that the following line in black’s setup.py seemed to be involved: "blackd=blackd:patched_main [d]",. When I specified a tagged version of black from just before that line was last edited (18.9b0), the environment setup ran through correctly.

Expected behavior

pre-commit should set up the black environment and then run black on the code to be committed.

Environment (please complete the following information):

• Version: Anything later than 18.9b0, including stable or master
• OS and Python version: Linux Mint 19.1 / Python 3.7.3

Does this bug also happen on master?

Yes.

[asottile]

yes, you can even combine the two as pre-commit install --install-hooks

we’re fixing the root cause in setuptools-scm though so that workaround shouldn’t be necessary indefinitely

[asottile]

I’ve created https://github.com/pypa/setuptools_scm/issues/381 to track this