Description:
Installing community/flake8 1:3.7.8-1 yields a /usr/bin/flake8 binary which throws an exception on every run (even with --help):

~~~
Traceback (most recent call last):
File "/usr/lib/python3.7/site-packages/flake8/plugins/manager.py", line 158, in load_plugin
self._load()
File "/usr/lib/python3.7/site-packages/flake8/plugins/manager.py", line 135, in _load
self._plugin = self.entry_point.load()
File "/usr/lib/python3.7/site-packages/entrypoints.py", line 82, in load
mod = import_module(self.module_name)
File "/usr/lib/python3.7/importlib/__init__.py", line 127, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
File "<frozen importlib._bootstrap>", line 983, in _find_and_load
File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 728, in exec_module
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "/usr/lib/python3.7/site-packages/pep8ext_naming.py", line 7, in <module>
from flake8_polyfill import options
ModuleNotFoundError: No module named 'flake8_polyfill'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/usr/bin/flake8", line 11, in <module>
load_entry_point('flake8==3.7.8', 'console_scripts', 'flake8')()
File "/usr/lib/python3.7/site-packages/flake8/main/cli.py", line 18, in main
app.run(argv)
File "/usr/lib/python3.7/site-packages/flake8/main/application.py", line 393, in run
self._run(argv)
File "/usr/lib/python3.7/site-packages/flake8/main/application.py", line 380, in _run
self.initialize(argv)
File "/usr/lib/python3.7/site-packages/flake8/main/application.py", line 363, in initialize
self.find_plugins()
File "/usr/lib/python3.7/site-packages/flake8/main/application.py", line 199, in find_plugins
self.check_plugins.load_plugins()
File "/usr/lib/python3.7/site-packages/flake8/plugins/manager.py", line 410, in load_plugins
plugins = list(self.manager.map(load_plugin))
File "/usr/lib/python3.7/site-packages/flake8/plugins/manager.py", line 297, in map
yield func(self.plugins[name], *args, **kwargs)
File "/usr/lib/python3.7/site-packages/flake8/plugins/manager.py", line 408, in load_plugin
return plugin.load_plugin()
File "/usr/lib/python3.7/site-packages/flake8/plugins/manager.py", line 165, in load_plugin
raise failed_to_load
flake8.exceptions.FailedToLoadPlugin: Flake8 failed to load plugin "N8" due to No module named 'flake8_polyfill'.
~~~

Running `python -m flake8` fails in the same way.

Installing flake8 with pip3 in a new, clean virtualenv yields the same version 3.7.8 but it does not exhibit the problem; therefore I suspect it's a packaging problem, not upstream.