No info on this, just wanted to point out that
http://core.trac.wordpress.org/ticket/6847, which is about the same thing, was closed as invalid, I think because the person closing it didn’t realize that it didn’t work for Atom or RSS2 feeds–probably because of http://core.trac.wordpress.org/ticket/8706
Also, there’s another forum thread on the same topic:
http://wordpress.org/support/topic/165044.
The patch submitted for 6847 might help you out; you could try it.
That ticket (6847) has been closed as “invalid”, but I don’t understand why–I suspect that the person who closed it didn’t realize that it doesn’t seem to work with Atom or RSS2 because of http://core.trac.wordpress.org/ticket/8706.
The patch that mystyman suggested works because of the inconsistency in 8706; the person who marked 6847 invalid is correct about how it /should/ work, but not about how it currently /does/ work, and until 6847 is fixed mystyman’s patch looks like the right answer to me.
Also, here’s another forum thread on it:
http://wordpress.org/support/topic/192997.
