bpo-44173: better approach for seeking in non-compressed ZipExtFile

[JuniorJPDJ]

At the moment stored ZipExtFile is being read to the place of seek like all other compressed variants.
It's not needed as it's possible to freely seek uncompressed file inside zip without this penalty.

Lots of apps depend on ZipExtFile seeking ability and this patch would increase performance and lower IO penalty significantly.

It disables CRC checking after first seek as it's impossible to check CRC if we are not reading whole file.

I've been using patched zipfile for almost a year now and I can say it works good ;)

https://bugs.python.org/issue44173

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[github-actions]

This PR is stale because it has been open for 30 days with no activity.

[JuniorJPDJ]

It would be cool to have it reviewed ;)

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[epicfaace]

Thanks for the PR -- can you undo all the unrelated formatting changes?

[JuniorJPDJ]

Thanks for the PR -- can you undo all the unrelated formatting changes?

@epicfaace Could you please tell me what exactly do you mean?

I had trouble with rebasing my PR a while ago, is that what you mean?

[terryjreedy]

People, especially non-git-experts, should use git merge upstream/main on their pr branch to update their pr, and then a normal push to their fork. Force-pushing is more powerful and more dangerous, and too often results in the sort of mess created here with dozens of bogus inclusions and review requests. Start over.

[JuniorJPDJ]

redone on #27737