audit: do not allow to use the python@2 formula

[iMichka]

python@2 is EOL, recommend to use system Python 2.

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew tests with your changes locally?

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[EricFromCanada]

This is a whitelist, not a blacklist.

[scpeters]

yeah, this section is about whitelisting keg-only dependencies, and I don't think python@2 is keg-only

perhaps it would be better to copy what is done to blacklist depending on git?

• brew/Library/Homebrew/dev-cmd/audit.rb

  Line 410 in ce83253

  problem "Don't use git as a dependency (it's always available)" if dep.name == "git"

[MikeMcQuaid]

Might be also worth porting that to reference uses_from_macos and providing an opt-out for relevant formulae depending on Git

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.

[fredvd]

We are still waiting for a final python 2.7.18 release in march/april 2020. It has already been moved to python@2 and is not the default Python up in brew searches. The system Python 2 is not up to date.

Why the rush to remove Python 2? It is still in use by a lot of people to support or port Applications in the coming to puthon 3. From the brew homepage:

""" Homebrew installs the stuff you need that Apple (or your Linux system) didn’t."""

Shouldn't that be leading instead of removing support for a still functioning language version. People still need this version, being it declared EOL or not. I find it a little bit paternalizing to add obstacles for installing Python 2 because some people think they know what is best for other people to 'need' on their systems.

[MikeMcQuaid]

People still need this version, being it declared EOL or not.

We are not interested in packaging and supporting EOL software.

some people think they know what is best for other people to 'need' on their systems.

This is literally the definition of "maintaining a package manager". Use brew extract if you still need python@2.

[iMichka]

FYI we won't ship 2.7.18. But this is not the place to discuss this (https://discourse.brew.sh is there for that).

And I need to come back to this PR.

[iMichka]

As the formula will be removed on Monday 10 February (Homebrew/homebrew-core#49796), this PR is not needed anymore.