[WIP] pylint and related cleanups

[pradyunsg]

pylint is a pretty noisy and powerful linter, capable of detecting code smells and in general is more capable than flake8. One place where pylint's superior rule disabling capabilities 1 will be handy is the typing import ignores, where we won't have to annotate the every line.

It does however need some configuration before being usable. My current plan is to use pylint for a bit, get to know which linting rules are actually useful, have a discussion about them then finally adopt them for us.

As an example, this PR contains cleanups for 2 rules, I think would be reasonable to adopt. There's a couple of extra changes here as well but they're basically parts that pylint flagged and I saw a cleaner way to fix them. I suggest reviewing this PR commit by commit and looking at the entire function's body when reviewing the changes.

If @pypa/pip-committers are okay with adding pylint to our CI, let's do this. :)

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TODO:

• What are the good rules?
• Figure out how to deal with existing code issues
  • Initial Plan: Fix them if trivial, otherwise # pylint: disable=....
• Add to CI

[xavfernandez]

I'm personally in favor 👍

[cjerdonek]

Some quick comments. I'm not opposed to using a new linter.

[pradyunsg]

Bwahahahaha. InstallRequirement bites here as well.

pylint crashes when run on req_install.py: pylint-dev/pylint#2591 (comment). After spending a more-than-justified amount of time digging through pylint's and astroid's code (in vain), I found a wonderful workaround, on pylint's issue tracker, for hitting the recursion limit:

--init-hook="import sys; sys.setrecursionlimit(10000)"

:')

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In other news, over the next 2 weeks, I have my semester-end exams. Hopefully for my academics, I'll be spotted rarely during that time. I might start working on #5051 in the mean time. :)

[pradyunsg]

I've added 4 new commits (no new rules yet) and rebased to include current master and PEP 517 changes. ✨

[BrownTruck]

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[BrownTruck]

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I am an automated bot and I have noticed that this pull request is not currently able to be merged. If you are able to either merge the master branch into this pull request or rebase this pull request against master then it will be eligible for code review and hopefully merging!

[BrownTruck]

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I am an automated bot and I have noticed that this pull request is not currently able to be merged. If you are able to either merge the master branch into this pull request or rebase this pull request against master then it will be eligible for code review and hopefully merging!

[pradyunsg]

Me wants to do this. Will do it, eventually. Closing due to lack of time.