Corrupted subjects on the archive website

Hi

Why do some message display with corrupted subjects on the mailing
list archives site?  The replies to the message below, but not the
message itself, are displayed with a corrupted subject.  They appear
fine in my mail client though.

http://www.postgresql.org/message-id/20150922134404.5050.75087@wrigleys.postgresql.org

The website shows "Re: [BUGS] BUG #13632: violation de l'intégrité rQ1|ɕѥ".
My mail client shows "Re: [BUGS] BUG #13632: violation de l'intégrité
référentielle".

The original message that displays correctly has the following raw header:

Subject: BUG #13632: violation de l'intégrité référentielle

The reply that doesn't display correctly has the following raw header:

Subject: Re: [BUGS] BUG #13632: violation de l'intégrité référentielle

A wise denizen of #postgresql pointed out that 'UTF-8' decoded as
base64 produces 'Q1\377' of which we see at least the 'Q1' in the
corrupted string.

Some other examples of corruption can be seen in the French, Spanish,
Russian etc sections:

http://www.postgresql.org/list/pgsql-es-ayuda/2015-09/

--
Thomas Munro
http://www.enterprisedb.com