Execution as python module broken

[cdce8p]

Steps to reproduce

git@github.com:PyCQA/pylint.git
cd pylint
Python3.8 -m venv venv-38
source venv-38/bin/activate
python -m pip install -U pip setuptools wheel
pip install -e .

python -m pylint a.py

Given a file a.py:

# can be empty

Current behavior

Traceback below

Expected behavior

No errors

Additional notes

Reverting #4153 solve the issue
At first glance it seems to be related to the handling of the Python virtual environment.

pylint --version output

pylint 2.8.0-dev1
astroid 2.5.1
Python 3.8.8 (v3.8.8:024d8058b0, Feb 19 2021, 08:48:17) 
[Clang 6.0 (clang-600.0.57)]

Traceback

Problem importing module logging.py: Unable to find module for /Users/.../pylint/pylint/checkers/logging.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module spelling.py: Unable to find module for /Users/.../pylint/pylint/checkers/spelling.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module python3.py: Unable to find module for /Users/.../pylint/pylint/checkers/python3.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module misc.py: Unable to find module for /Users/.../pylint/pylint/checkers/misc.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module typecheck.py: Unable to find module for /Users/.../pylint/pylint/checkers/typecheck.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module variables.py: Unable to find module for /Users/.../pylint/pylint/checkers/variables.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module deprecated.py: Unable to find module for /Users/.../pylint/pylint/checkers/deprecated.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module base_checker.py: Unable to find module for /Users/.../pylint/pylint/checkers/base_checker.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module format.py: Unable to find module for /Users/.../pylint/pylint/checkers/format.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module mapreduce_checker.py: Unable to find module for /Users/.../pylint/pylint/checkers/mapreduce_checker.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module imports.py: Unable to find module for /Users/.../pylint/pylint/checkers/imports.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module utils.py: Unable to find module for /Users/.../pylint/pylint/checkers/utils.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module raw_metrics.py: Unable to find module for /Users/.../pylint/pylint/checkers/raw_metrics.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module newstyle.py: Unable to find module for /Users/.../pylint/pylint/checkers/newstyle.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module exceptions.py: Unable to find module for /Users/.../pylint/pylint/checkers/exceptions.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module classes.py: Unable to find module for /Users/.../pylint/pylint/checkers/classes.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module stdlib.py: Unable to find module for /Users/.../pylint/pylint/checkers/stdlib.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module async.py: Unable to find module for /Users/.../pylint/pylint/checkers/async.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module refactoring: Unable to find module for /Users/.../pylint/pylint/checkers/refactoring in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module similar.py: Unable to find module for /Users/.../pylint/pylint/checkers/similar.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module design_analysis.py: Unable to find module for /Users/.../pylint/pylint/checkers/design_analysis.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module base.py: Unable to find module for /Users/.../pylint/pylint/checkers/base.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module strings.py: Unable to find module for /Users/.../pylint/pylint/checkers/strings.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module ureports: Unable to find module for /Users/.../pylint/pylint/reporters/ureports in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module json_reporter.py: Unable to find module for /Users/.../pylint/pylint/reporters/json_reporter.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module reports_handler_mix_in.py: Unable to find module for /Users/.../pylint/pylint/reporters/reports_handler_mix_in.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module base_reporter.py: Unable to find module for /Users/.../pylint/pylint/reporters/base_reporter.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module collecting_reporter.py: Unable to find module for /Users/.../pylint/pylint/reporters/collecting_reporter.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Problem importing module text.py: Unable to find module for /Users/.../pylint/pylint/reporters/text.py in /Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8, 
/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages, 
/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/brain
Traceback (most recent call last):
  File "/Users/.../pylint/pylint/lint/pylinter.py", line 511, in _load_reporter
    reporter_class = self._load_reporter_class()
  File "/Users/.../pylint/pylint/lint/pylinter.py", line 519, in _load_reporter_class
    module = modutils.load_module_from_name(modutils.get_module_part(qname))
  File "/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/modutils.py", line 435, in get_module_part
    file_from_modpath(
  File "/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/modutils.py", line 331, in file_from_modpath
    return file_info_from_modpath(modpath, path, context_file).location
  File "/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/modutils.py", line 381, in file_info_from_modpath
    return _spec_from_modpath(modpath, path, context)
  File "/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/modutils.py", line 612, in _spec_from_modpath
    found_spec = spec.find_spec(modpath, path)
  File "/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/interpreter/_import/spec.py", line 368, in find_spec
    finder, spec = _find_spec_with_path(
  File "/Users/.../pylint/venv-38/lib/python3.8/site-packages/astroid/interpreter/_import/spec.py", line 337, in _find_spec_with_path
    raise ImportError("No module named %s" % ".".join(module_parts))
ImportError: No module named text

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "/Users/.../pylint/pylint/__main__.py", line 20, in <module>
    pylint.run_pylint()
  File "/Users/.../pylint/pylint/__init__.py", line 22, in run_pylint
    PylintRun(sys.argv[1:])
  File "/Users/.../pylint/pylint/lint/run.py", line 264, in __init__
    linter.load_default_plugins()
  File "/Users/.../pylint/pylint/lint/pylinter.py", line 480, in load_default_plugins
    self._load_reporter()
  File "/Users/.../pylint/pylint/lint/pylinter.py", line 513, in _load_reporter
    raise exceptions.InvalidReporterError(name) from e
pylint.exceptions.InvalidReporterError: text

[sbraz]

I can't reproduce except if I cd into venv/lib/python3.9/site-packages, what is your working directory when running this? I assume it would only fail if you're running the module from the parent of the package folder.

[cdce8p]

My mistake, I just assumed it would occur in a normal context.
I noticed the issue in my pylint dev environment, since this the the VS Code command for debugging.

My setup:

git@github.com:PyCQA/pylint.git
cd pylint
Python3.8 -m venv venv-38
source venv-38/bin/activate
python -m pip install -U pip setuptools wheel
pip install -e .

touch a.py
python -m pylint a.py

I also did just look at sys.path. It seems that in editable mode the CWD is added as last path.
Before:

['/Users/.../pylint',
 '/Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip',
 '/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8',
 '/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload',
 '/Users/.../pylint/venv-38/lib/python3.8/site-packages',
 '/Users/.../pylint']

After:

['/Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip',
 '/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8',
 '/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload',
 '/Users/.../pylint/venv-38/lib/python3.8/site-packages']

This was the output with the old version

['/Library/Frameworks/Python.framework/Versions/3.8/lib/python38.zip',
 '/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8',
 '/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/lib-dynload',
 '/Users/.../pylint/venv-38/lib/python3.8/site-packages',
 '/Users/.../pylint']

--
As you can see here: https://bugs.python.org/msg313966, the CWD is only added as first element in sys.path. So the previous version should be enough. I would recommend to revert #4153.

@sbraz Did you had any issues before you submitted the MR?

[sbraz]

@cdce8p Yup, it's explained in my PR (it fixes #3636). If PYTHONPATH ends or starts with a colon, two tests fail because the CWD is added twice to sys.path.

[cdce8p]

Opened #4164 to address the issue