How to change EWW page encoding?

[cantoraz]

Open this page Gnus history for example. EWW renders it as below (notice \253 and \273 characters):

A chromium-based browser can detect page encoding properly (seems to be ISO-8859-1, but firefox can not):

I tried z e (eww-set-character-encoding) to choose ISO-8859-1, ISO-8859-15, Latin-1, Latin-0, etc. All of them had no effect.

So, how can I tell EWW a proper encoding to display page properly?