Description: ModuleNotFoundError: No module named 'pip._vendor.packaging.tags'


Additional info:
* package version(s) 20.3.1
* config and/or log files etc.

Traceback (most recent call last):
File "/usr/bin/pip", line 33, in <module>
sys.exit(load_entry_point('pip==20.3.1', 'console_scripts', 'pip')())
File "/usr/bin/pip", line 25, in importlib_load_entry_point
return next(matches).load()
File "/usr/lib/python3.9/importlib/metadata.py", line 77, in load
module = import_module(match.group('module'))
File "/usr/lib/python3.9/importlib/__init__.py", line 127, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 790, in exec_module
File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
File "/usr/lib/python3.9/site-packages/pip/_internal/cli/main.py", line 10, in <module>
from pip._internal.cli.autocompletion import autocomplete
File "/usr/lib/python3.9/site-packages/pip/_internal/cli/autocompletion.py", line 9, in <module>
from pip._internal.cli.main_parser import create_main_parser
File "/usr/lib/python3.9/site-packages/pip/_internal/cli/main_parser.py", line 7, in <module>
from pip._internal.cli import cmdoptions
File "/usr/lib/python3.9/site-packages/pip/_internal/cli/cmdoptions.py", line 30, in <module>
from pip._internal.models.target_python import TargetPython
File "/usr/lib/python3.9/site-packages/pip/_internal/models/target_python.py", line 3, in <module>
from pip._internal.utils.compatibility_tags import get_supported, version_info_to_nodot
File "/usr/lib/python3.9/site-packages/pip/_internal/utils/compatibility_tags.py", line 8, in <module>
from pip._vendor.packaging.tags import (
ModuleNotFoundError: No module named 'pip._vendor.packaging.tags'


* link to upstream bug report, if any

Steps to reproduce:

- install python-pip
- run pip