Double %-encoding in "respond to this messages" from mailing-list archives.

Hi,

The mailing-list archives have a mailto: link marked "respond to this 
messages" with the suitable In-Reply-To and References headers so that a 
reply can be properly threaded, even when the author did not have the 
original message in their email client.

See for example at the bottom near "Mail actions":
http://lists.w3.org/Archives/Public/www-style/2012Sep/0454.html

The feature is great, except it does not quite work. There is some 
double %-encoding going on, and References: <_foo_> is encoded as 
References=%253C_foo_%253E instead of References=%3C_foo_%3E, and thus 
decoded as References: %3C_foo_%3E

Please let me know if I can help further with fixing this.

Regards,
-- 
Simon Sapin