Homebrew-core: Upgrading pip breaks pip

[Slooz]

• [x] are reporting a bug others will be able to reproduce and not asking a question or requesting software. If you're not sure or want to ask a question do so on our Discourse: https://discourse.brew.sh. To get software added or changed in Homebrew please file a Pull Request
• [x] have a problem with brew install (or upgrade, reinstall) a single, Homebrew/homebrew-core formula (not cask) on macOS? If it's a general brew problem please file this issue at Homebrew/brew: https://github.com/Homebrew/brew/issues/new/choose. If it's a Linux problem please file this issue at https://github.com/Homebrew/linuxbrew-core/issues/new/choose. If it's a brew cask problem please file this issue at https://github.com/Homebrew/homebrew-cask/issues/new/choose. If it's a tap (e.g. Homebrew/homebrew-php) problem please file this issue at the tap.
• [x] ran brew update and can still reproduce the problem?
• [x] ran brew doctor, fixed all issues and can still reproduce the problem?
• [x] ran brew gist-logs <formula> (where <formula> is the name of the formula that failed) and included the output link?
• [ ] if brew gist-logs didn't work: ran brew config and brew doctor and included their output with your issue?

See Gist logs.

I'm trying to upgrade pip because it's good to keep your software updated.

After upgrading pip, pip throws an exception:

Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 583, in _build_master
    ws.require(__requires__)
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 900, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 791, in resolve
    raise VersionConflict(dist, req).with_context(dependent_req)
pkg_resources.VersionConflict: (pip 19.2.3 (/usr/local/lib/python3.7/site-packages), Requirement.parse('pip==19.1.1'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/opt/python/libexec/bin/pip", line 6, in <module>
    from pkg_resources import load_entry_point
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 3241, in <module>
    @_call_aside
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 3225, in _call_aside
    f(*args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 3254, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 585, in _build_master
    return cls._build_from_requirements(__requires__)
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 598, in _build_from_requirements
    dists = ws.resolve(reqs, Environment())
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 786, in resolve
    raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'pip==19.1.1' distribution was not found and is required by the application

Reproduction instructions:

1. Shell $ brew install python

```Shell
==> Downloading https://homebrew.bintray.com/bottles/python-3.7.4.mojave.bottle.tar.gz
Already downloaded: /Users/Czelusniak_Krzysztof/Library/Caches/Homebrew/downloads/ffcfe300e2ad205387a2bdd27185d98d64621578d26d2f6ccbbcd091ff799fc8--python-3.7.4.mojave.bottle.tar.gz
==> Pouring python-3.7.4.mojave.bottle.tar.gz
==> /usr/local/Cellar/python/3.7.4/bin/python3 -s setup.py --no-user-cfg install --force --verbose --install-scripts=/usr/local/Cellar/python/3.7.4/bin --install-lib=/usr/local/lib/python3.7/site-packages --single-version-externally-manag
==> /usr/local/Cellar/python/3.7.4/bin/python3 -s setup.py --no-user-cfg install --force --verbose --install-scripts=/usr/local/Cellar/python/3.7.4/bin --install-lib=/usr/local/lib/python3.7/site-packages --single-version-externally-manag
==> /usr/local/Cellar/python/3.7.4/bin/python3 -s setup.py --no-user-cfg install --force --verbose --install-scripts=/usr/local/Cellar/python/3.7.4/bin --install-lib=/usr/local/lib/python3.7/site-packages --single-version-externally-manag
==> Caveats
Python has been installed as
  /usr/local/bin/python3

Unversioned symlinks `python`, `python-config`, `pip` etc. pointing to
`python3`, `python3-config`, `pip3` etc., respectively, have been installed into
  /usr/local/opt/python/libexec/bin

If you need Homebrew's Python 2.7 run
  brew install python@2

You can install Python packages with
  pip3 install <package>
They will install into the site-package directory
  /usr/local/lib/python3.7/site-packages

See: https://docs.brew.sh/Homebrew-and-Python
==> Summary
🍺  /usr/local/Cellar/python/3.7.4: 3,865 files, 60MB
```

1. Shell $ python -m pip install --upgrade pip

```Shell
Collecting pip
  Using cached https://files.pythonhosted.org/packages/30/db/9e38760b32e3e7f40cce46dd5fb107b8c73840df38f0046d8e6514e675a1/pip-19.2.3-py2.py3-none-any.whl
Installing collected packages: pip
  Found existing installation: pip 19.1.1
    Uninstalling pip-19.1.1:
      Successfully uninstalled pip-19.1.1
Successfully installed pip-19.2.3
```

1. Shell $ pip

```Shell
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 583, in _build_master
    ws.require(__requires__)
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 900, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 791, in resolve
    raise VersionConflict(dist, req).with_context(dependent_req)
pkg_resources.VersionConflict: (pip 19.2.3 (/usr/local/lib/python3.7/site-packages), Requirement.parse('pip==19.1.1'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/opt/python/libexec/bin/pip", line 6, in <module>
    from pkg_resources import load_entry_point
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 3241, in <module>
    @_call_aside
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 3225, in _call_aside
    f(*args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 3254, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 585, in _build_master
    return cls._build_from_requirements(__requires__)
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 598, in _build_from_requirements
    dists = ws.resolve(reqs, Environment())
  File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 786, in resolve
    raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'pip==19.1.1' distribution was not found and is required by the application
```

See related links:

• Homebrew Community
• pip's GitHub Issues

[dfkotz]

I'm seeing the same issue.

[dfkotz]

Either homebrew fixed something, or the following fixed the problem for me.

[MacOS:~]$ sudo -H python3 -m pip install --force-reinstall pip
Collecting pip
  Downloading https://files.pythonhosted.org/packages/30/db/9e38760b32e3e7f40cce46dd5fb107b8c73840df38f0046d8e6514e675a1/pip-19.2.3-py2.py3-none-any.whl (1.4MB)
     |████████████████████████████████| 1.4MB 3.2MB/s 
Installing collected packages: pip
  Found existing installation: pip 19.2.3
    Uninstalling pip-19.2.3:
      Successfully uninstalled pip-19.2.3
Successfully installed pip-19.2.3
[MacOS:~]$ pip3

Usage:   
  pip3 <command> [options]
...

[Slooz]

@dfkotz, one thing to note is that I'm invoking pip, not pip3. I added /usr/local/opt/python/libexec/bin to my path, so invoking pip should invoke pip3.

[dfkotz]

I still use python2 sometimes so my pip invokes pip2, and thus I must use pip3 when I mean pip3.

[Slooz]

Makes sense, but my point is that /usr/local/opt/python/libexec/bin/pip throws the error that I reported, but it should invoke pip3

[simonweil]

Same thing happens to me when upgrading pip of python@2...

[CharlyRipp]

Just ran into this today as well.

pkg_resources.VersionConflict: (pip 19.3 (/usr/local/lib/python3.7/site-packages), Requirement.parse('pip==19.1.1'))

Attempted what worked for @dfkotz (sudo -H python3 -m pip install --force-reinstall pip) but didn't work.

Invoking pip3 however does still function as well as python -m pip.

Ended up reverting, which got tricky for some reason. Had to

brew install python@2
brew uninstall python@3 --ignore-dependencies
sudo rm -rf /usr/local/lib/python3.7
brew install python@3

[sdavids]

For the interim a workaround would be to change every occurrence of 19.2.3 with 19.3.1 in file /usr/local/opt/python/libexec/bin/pip:

$ sed -i "" 's/19\.2\.3/19.3.1/' /usr/local/opt/python/libexec/bin/pip

[fxcoudert]

We have since then upgraded pip in the python formulas