dd-mmm-yyyy which corresponds to %d-%b-%Y.

Only with some locales. Sometimes, %d-%b-%Y gives me 08-úno-2021.

Would it be reasonable to change PEP 1 to a format that's independent of locale, like %Y-%m-%d (2021-02-08)?

Can we first land this? There are too many pending PRs relating to this minor issue.

Re: the idea of using a different format needs much more consideration before it can be made to work -- personally I'd prefer to keep the current format and just state it has to be the English locale (like the rest of the text has to be in English).

Sure – if you've considered the locale issue, go ahead!

(I'm just raising the point because, IMO, this is the time it should be considered. The more automation is built around it, the harder it'll be to change.)

@gvanrossum I only did this to mine the PEPs for creation date details, so my itch is scratched at this point. 😉