use pre-commit for python files

[3nids]

This enables pre-commit hook for Python files and disable Python formatting from prepare-commit.sh

I've only added: pyupgrade, black and isort without specific config for the sake of simplicity/clarity. See config for details.

I've also enabled auto-fix for PRs (will be effective when we activate pre-commit.ci).

We've recently succeeded at using clang-format on a sipified project (see kadas-albireo/kadas-albireo2#175). So this is a first small step before starting to touch at cpp code.

[github-actions]

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[3nids]

@troopa81 @nyalldawson @elpaso @m-kuhn any feedback welcome!

[troopa81]

Would that mean that if you're the first to push a PR after a hook update (let's say black rules for instance), you're gonna push a lot of modified files which are not related to your PR? Or is there an auto PR/commit pushed automatically on the repo on update?

[3nids]

autoupdate is to update the tools used, so nothing related to the source code.

if there's a hook update, there's not that many changes brought. And in a PR, IIRC only the modified files are tested.

[m-kuhn]

I am a big fan of pre-commit and supportive of actions to move there (I even tried to launch an unsuccessful crowdfunding campaign to sponsor @elpaso 's QEP). I also like black. I did not review the changes or configuration yet.

The main question here for me is, how this coexists with existing pre-commit hooks, in terms of local development configuration? Does one call the other (pre-commit the existing prepare_commit.sh or vice versa) or can the system be configured to run both in a different way)?

[nyalldawson]

Can you create a .git-blame-ignore-revs file and exclude the "run-precommit" commit from it? See https://gist.github.com/kateinoigakukun/b0bc920e587851bfffa98b9e279175f2

And I'm hugely in favour of this move!

[3nids]

how this coexists with existing pre-commit hooks

good point, I've added prepare_commit to the pre-commit hook: f24de2e

Can you create a .git-blame-ignore-revs file and exclude the "run-precommit" commit from it?

good catch. I've added the file. I suppose we can wait to merge to update that file with the proper commit (in case it's rebased)?

[3nids]

In case there is no further discussions, I would merge it in a couple of days.

I would assume the general acceptance is fine since there were no objections in @elpaso's QEP qgis/QGIS-Enhancement-Proposals#265

[m-kuhn]

No objections so far but positive feedback. I'm in favor of merging this.