Non-ASCII subjects garbled in thread view of the mail archives

[Yavor Doganov]

[ Perhaps address@hidden is the right place to report this -- if so,
  please bounce/forward the message and sorry for bothering. ]

I have a vague feeling that I've reported this before, some (many?)
years ago.  A Subject: of an email message in UTF-8 encoding but
containing other than US-ASCII characters appears garbled in the
thread view of a mailing list archive:

https://lists.nongnu.org/archive/html/gug-bg-herd/2019-11/threads.html

This makes it difficult to locate a particular message when an
archived URL is needed and is also a nuisance when a new list
subscriber decides to read some messages from the time before he
became a list member.

That's a minor annoyance probably affecting only a few lists
(www.gnu.org translation teams come to mind) but it's still something
worth fixing, I guess.