I subscribe to source-changes@netbsd.org and got a message like this:

  From: "Fred" <fred_redacted@netbsd.org>
  Subject: CVS commit: src/sys/arch/powerpc/booke
  To: source-changes@NetBSD.org
  Date: Thu, 5 Jul 2012 17:25:36 +0000 (50 minutes, 55 seconds ago)
  Reply-To: source-changes-d@NetBSD.org
  Mail-Followup-To: source-changes-d@NetBSD.org                                   
I hit 'f' and asked a question about the change.  gnus composed a mail
which was To: fred and CC: source-changes.

I do have broken-reply-to set on some lists, but this is a funny case;
the intent is to have replies that do go to the list go to a discuss
list, not to force people not to send private replies.

So I'm curious what the collective gnus wisdom is here.

(emacs 23, gnus fairly recent git head)