Bug#791506: [www.debian.org] Content negotiation doesn't work properly with pt_BR at the Release Notes web page

Package: www.debian.org
Followup-For: Bug #791506

Dear Maintainer,

When I have *both* pt-BR and pt locales enabled in my browser (Firefox 102),
then this bug appears: the 'pt' Release Notes links appear in bold instead of
the expected 'pt_BR' links appearing in bold.

When I remove pt, then the page is negotiated to a fallback language (en-based
with my browser settings).

Is it possible that content-negotiation is only enabled currently for
two-character language codes, and not for country+locale combinations?

Thank you,
James