pre-commit install silently fails when running in git-bash

describe your issue

I am actually doing dev work on pyscaffold, which uses pre-commit. Problems there led me to track the problem back to pre-commit. Running on Windows 10 in git-bash the command precommit install produces no output, but has a return code of 1.

I tracked the problem to sys.stderr being used without checking that it is not None It happens at main.py line 335 - args = parser.parse_args(argv)

pre-commit --version

2.17.0

.pre-commit-config.yaml

just an empty file

~/.cache/pre-commit/pre-commit.log (if present)

I tracked it down and found the exception and printed it for you.

Traceback (most recent call last): File “C:\Users\julie\juliehome.venvs\pyscaffold\lib\site-packages\pre_commit\main.py”, line 342, in main args = parser.parse_args(argv) File “C:\Users\julie\AppData\Local\Programs\Python\Python310\lib\argparse.py”, line 1825, in parse_args args, argv = self.parse_known_args(args, namespace) File “C:\Users\julie\AppData\Local\Programs\Python\Python310\lib\argparse.py”, line 1858, in parse_known_args namespace, args = self._parse_known_args(args, namespace) File “C:\Users\julie\AppData\Local\Programs\Python\Python310\lib\argparse.py”, line 2070, in _parse_known_args stop_index = consume_positionals(start_index) File “C:\Users\julie\AppData\Local\Programs\Python\Python310\lib\argparse.py”, line 2026, in consume_positionals take_action(action, args) File “C:\Users\julie\AppData\Local\Programs\Python\Python310\lib\argparse.py”, line 1935, in take_action action(self, namespace, argument_values, option_string) File “C:\Users\julie\AppData\Local\Programs\Python\Python310\lib\argparse.py”, line 1213, in call subnamespace, arg_strings = parser.parse_known_args(arg_strings, None) File “C:\Users\julie\AppData\Local\Programs\Python\Python310\lib\argparse.py”, line 1858, in parse_known_args namespace, args = self._parse_known_args(args, namespace) File “C:\Users\julie\AppData\Local\Programs\Python\Python310\lib\argparse.py”, line 2092, in _parse_known_args self._get_value(action, action.default)) File “C:\Users\julie\AppData\Local\Programs\Python\Python310\lib\argparse.py”, line 2483, in _get_value result = type_func(arg_string) File “C:\Users\julie\juliehome.venvs\pyscaffold\lib\site-packages\pre_commit\color.py”, line 94, in use_color sys.stderr.isatty() and AttributeError: ‘NoneType’ object has no attribute ‘isatty’

[asottile]

please do not, stderr should never be None. this is not “defensive programming” this is complexity against an impossible situation

[julie777]

I’ve done much more research on this issue and in my case there is both the problem with pip22 and a problem with git-bash and others using mintty.

thanks for your help