Python issue after updating pip and setuptools

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I have encountered what I think is a bug but wanted to run it past more experienced users.

After installing python3 brew install python
And running pip list --outdated

$ pip list --outdated
Package     Version Latest Type
----------- ------- ------ -----
dnspython   1.16.0  2.0.0  wheel
pip         20.1.1  20.2.3 wheel
pyee        7.0.2   7.0.3  wheel
pytesseract 0.3.5   0.3.6  sdist
setuptools  49.2.0  50.3.0 wheel
tzlocal     1.5.1   2.1    wheel

Using the instructions on the Homebrew documentation for python on updating pip and setuptools I ran the following commands:

python3 -m pip install --upgrade setuptools
python3 -m pip install --upgrade pip

This resulted in many issues for my brew install of python.
Python installed aliases were replaced with executables and aliases became corrupted and running brew test python resulted in errors:

$ brew test python3
==> Testing python@3.8
==> /usr/local/Cellar/python@3.8/3.8.5/bin/python3.8 -c import sqlite3
==> /usr/local/Cellar/python@3.8/3.8.5/bin/python3.8 -c import tkinter; root = tkinter.Tk()
==> /usr/local/Cellar/python@3.8/3.8.5/bin/python3.8 -c import _gdbm
==> /usr/local/Cellar/python@3.8/3.8.5/bin/python3.8 -c import zlib
==> /usr/local/Cellar/python@3.8/3.8.5/bin/pip3 list --format=columns
Last 15 lines from /Users/admin/Library/Logs/Homebrew/python@3.8/test.05.pip3:
  File "/usr/local/lib/python3.8/site-packages/pip/_internal/utils/misc.py", line 21, in <module>
    from pip._vendor import pkg_resources
  File "/usr/local/lib/python3.8/site-packages/pip/_vendor/pkg_resources/__init__.py", line 3252, in <module>
    def _initialize_master_working_set():
  File "/usr/local/lib/python3.8/site-packages/pip/_vendor/pkg_resources/__init__.py", line 3235, in _call_aside
    f(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/pip/_vendor/pkg_resources/__init__.py", line 3264, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/usr/local/lib/python3.8/site-packages/pip/_vendor/pkg_resources/__init__.py", line 585, in _build_master
    return cls._build_from_requirements(__requires__)
  File "/usr/local/lib/python3.8/site-packages/pip/_vendor/pkg_resources/__init__.py", line 598, in _build_from_requirements
    dists = ws.resolve(reqs, Environment())
  File "/usr/local/lib/python3.8/site-packages/pip/_vendor/pkg_resources/__init__.py", line 786, in resolve
    raise DistributionNotFound(req, requirers)
pip._vendor.pkg_resources.DistributionNotFound: The 'pip==20.1.1' distribution was not found and is required by the application
Error: python@3.8: failed
An exception occurred within a child process:
  BuildError: Failed executing: /usr/local/Cellar/python@3.8/3.8.5/bin/pip3 list --format=columns
/usr/local/Homebrew/Library/Homebrew/formula.rb:2025:in `block in system'
/usr/local/Homebrew/Library/Homebrew/formula.rb:1963:in `open'
/usr/local/Homebrew/Library/Homebrew/formula.rb:1963:in `system'
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/python@3.8.rb:344:in `block in <class:PythonAT38>'
/usr/local/Homebrew/Library/Homebrew/formula.rb:1834:in `block (3 levels) in run_test'
/usr/local/Homebrew/Library/Homebrew/utils.rb:492:in `with_env'
/usr/local/Homebrew/Library/Homebrew/formula.rb:1833:in `block (2 levels) in run_test'
/usr/local/Homebrew/Library/Homebrew/formula.rb:893:in `with_logging'
/usr/local/Homebrew/Library/Homebrew/formula.rb:1832:in `block in run_test'
/usr/local/Homebrew/Library/Homebrew/mktemp.rb:57:in `block in run'
/usr/local/Homebrew/Library/Homebrew/mktemp.rb:57:in `chdir'
/usr/local/Homebrew/Library/Homebrew/mktemp.rb:57:in `run'
/usr/local/Homebrew/Library/Homebrew/formula.rb:2074:in `mktemp'
/usr/local/Homebrew/Library/Homebrew/formula.rb:1826:in `run_test'
/usr/local/Homebrew/Library/Homebrew/test.rb:37:in `block in <main>'
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.6.3_2/lib/ruby/2.6.0/timeout.rb:93:in `block in timeout'
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.6.3_2/lib/ruby/2.6.0/timeout.rb:33:in `block in catch'
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.6.3_2/lib/ruby/2.6.0/timeout.rb:33:in `catch'
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.6.3_2/lib/ruby/2.6.0/timeout.rb:33:in `catch'
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.6.3_2/lib/ruby/2.6.0/timeout.rb:108:in `timeout'
/usr/local/Homebrew/Library/Homebrew/test.rb:36:in `<main>'

I thought maybe running brew unlink python && brew link python would help:

Unlinking /usr/local/Cellar/python@3.8/3.8.5... 22 symlinks removed
Linking /usr/local/Cellar/python@3.8/3.8.5... 
Error: Could not symlink bin/easy_install-3.8
Target /usr/local/bin/easy_install-3.8
already exists. You may want to remove it:
  rm '/usr/local/bin/easy_install-3.8'

To force the link and overwrite all conflicting files:
  brew link --overwrite python@3.8

To list all files that would be deleted:
  brew link --overwrite --dry-run python@3.8

So I follow directions and run:

brew link --overwrite python@3.8
Linking /usr/local/Cellar/python@3.8/3.8.5... 25 symlinks created

Now the previous executables are replaced with aliases and executables have been installed inside: /usr/local/Cellar/python@3.8/3.8.5/bin

brew test python3 still gives me the same errors as above.

Checking version for pip inside /usr/local/bin

$ /usr/local/bin/pip -V
pip 20.2.2 from /usr/local/lib/python3.8/site-packages/pip (python 3.8)

That’s weird. It seems all of my python aliases are messed up after updating pip and setuptools using the command that Homebrew recommends.

Look at this error when trying to get version of pip3 by path.

$ /usr/local/Cellar/python@3.8/3.8.5/bin/pip3 -V
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/pip/_vendor/pkg_resources/__init__.py", line 583, in _build_master
    ws.require(__requires__)
  File "/usr/local/lib/python3.8/site-packages/pip/_vendor/pkg_resources/__init__.py", line 900, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/local/lib/python3.8/site-packages/pip/_vendor/pkg_resources/__init__.py", line 791, in resolve
    raise VersionConflict(dist, req).with_context(dependent_req)
pip._vendor.pkg_resources.VersionConflict: (pip 20.2.2 (/usr/local/lib/python3.8/site-packages), Requirement.parse('pip==20.1.1'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/Cellar/python@3.8/3.8.5/bin/pip3", line 33, in <module>
    sys.exit(load_entry_point('pip==20.1.1', 'console_scripts', 'pip3')())
  File "/usr/local/Cellar/python@3.8/3.8.5/bin/pip3", line 25, in importlib_load_entry_point
    return next(matches).load()
  File "/usr/local/Cellar/python@3.8/3.8.5/Frameworks/Python.framework/Versions/3.8/lib/python3.8/importlib/metadata.py", line 77, in load
    module = import_module(match.group('module'))
  File "/usr/local/Cellar/python@3.8/3.8.5/Frameworks/Python.framework/Versions/3.8/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/usr/local/lib/python3.8/site-packages/pip/_internal/cli/main.py", line 10, in <module>
    from pip._internal.cli.autocompletion import autocomplete
  File "/usr/local/lib/python3.8/site-packages/pip/_internal/cli/autocompletion.py", line 9, in <module>
    from pip._internal.cli.main_parser import create_main_parser
  File "/usr/local/lib/python3.8/site-packages/pip/_internal/cli/main_parser.py", line 7, in <module>
    from pip._internal.cli import cmdoptions
  File "/usr/local/lib/python3.8/site-packages/pip/_internal/cli/cmdoptions.py", line 23, in <module>
    from pip._internal.cli.progress_bars import BAR_TYPES
  File "/usr/local/lib/python3.8/site-packages/pip/_internal/cli/progress_bars.py", line 12, in <module>
    from pip._internal.utils.logging import get_indentation
  File "/usr/local/lib/python3.8/site-packages/pip/_internal/utils/logging.py", line 18, in <module>
    from pip._internal.utils.misc import ensure_dir
  File "/usr/local/lib/python3.8/site-packages/pip/_internal/utils/misc.py", line 21, in <module>
    from pip._vendor import pkg_resources
  File "/usr/local/lib/python3.8/site-packages/pip/_vendor/pkg_resources/__init__.py", line 3252, in <module>
    def _initialize_master_working_set():
  File "/usr/local/lib/python3.8/site-packages/pip/_vendor/pkg_resources/__init__.py", line 3235, in _call_aside
    f(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/pip/_vendor/pkg_resources/__init__.py", line 3264, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/usr/local/lib/python3.8/site-packages/pip/_vendor/pkg_resources/__init__.py", line 585, in _build_master
    return cls._build_from_requirements(__requires__)
  File "/usr/local/lib/python3.8/site-packages/pip/_vendor/pkg_resources/__init__.py", line 598, in _build_from_requirements
    dists = ws.resolve(reqs, Environment())
  File "/usr/local/lib/python3.8/site-packages/pip/_vendor/pkg_resources/__init__.py", line 786, in resolve
    raise DistributionNotFound(req, requirers)
pip._vendor.pkg_resources.DistributionNotFound: The 'pip==20.1.1' distribution was not found and is required by the application

To fix the issue I try to go back to the default install without updating pip and setuptools. So, I
brew uninstall --ignore-dependencies python && brew install python to test my theory and voila…

$ brew test python 
==> Testing python@3.8
==> /usr/local/Cellar/python@3.8/3.8.5/bin/python3.8 -c import sqlite3
==> /usr/local/Cellar/python@3.8/3.8.5/bin/python3.8 -c import tkinter; root = tkinter.Tk()
==> /usr/local/Cellar/python@3.8/3.8.5/bin/python3.8 -c import _gdbm
==> /usr/local/Cellar/python@3.8/3.8.5/bin/python3.8 -c import zlib
==> /usr/local/Cellar/python@3.8/3.8.5/bin/pip3 list --format=columns

Everything is functioning again but I am conerned about the line in the error message:

pip._vendor.pkg_resources.DistributionNotFound: The 'pip==20.1.1' distribution was not found and is required by the application

It seems maybe the requirements aren't being updated when a user upgrades to the latest version of pip and setup tools as suggested on the homebrew python documentation.

Any ideas on how to get around this or if this is a "bug"?