>> These character encodings are legacy, but are still used.
>
> Do you have an idea of how many users still have documents stored or exchanged using these encodings?

Hmm, I guess iso-2022-jp codec is still default charset of MUA (Mail
User Agent) on Japanese Windows platform. But I'm not sure how many so
I'll investigate, wait a few days.

> The patch is not trivial, the legacy japanese codecs are complex and so error prone :-/

Ya, this patch has some refactoring. However, existing tests have
passed and adding encoding codecs wouldn't affect other codecs
basically. Why do you think it's "error plone"?

> For previous requests to add new codecs, we closed issues as wontfix and we suggested to share the codecs at the Python Cheeseshop (PyPI). Here it's more complex because C code is modified to implement the new encodings.

Could you show me previous requests? I can understand C code modifying
is higher cost to review. However, we have codec tests and it wouldn't
affect other codecs, I think.