gh-124452: Fix header mismatches when folding/unfolding with email message

[RanKKI]

Fix: #124452

• Issue: gh-124452

[ghost]

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[bedevere-app[bot]]

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If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[bedevere-app[bot]]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[RanKKI]

I have made the requested changes; please review again

[bedevere-app[bot]]

Thanks for making the requested changes!

@bitdancer: please review the changes made to this pull request.

[rruuaanng]

Please specify the method. It seems that you haven't read this link carefully ：）

[bitdancer]

Thanks, RanKII. Sorry, I missed the update notification, and I only just checked back on the PR.

[miss-islington-app[bot]]

Thanks @RanKKI for the PR, and @bitdancer for merging it 🌮🎉.. I'm working now to backport this PR to: 3.12. 🐍🍒⛏🤖

[miss-islington-app[bot]]

Thanks @RanKKI for the PR, and @bitdancer for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13. 🐍🍒⛏🤖

[bedevere-app[bot]]

GH-126916 is a backport of this pull request to the 3.12 branch.

[bedevere-app[bot]]

GH-126917 is a backport of this pull request to the 3.13 branch.