Sorting threads after gathering threads

[Michael Welsh Duggan]

I am on an automated mailing list which I automatically filter into a
separate Gnus group.  Each message on this list is an individual,
non-threaded messages.  Many of these messages are indeed related, and
this can be determined by the subject.  I have put my own
subject-simplifying function in the `gnus-simplify-subject-functions'
variable for this group.  This correctly gathers the individual messages
into threads.

Now the problem: I want to sort the *Summary* buffer like this: Each
thread is sorted from the oldest to the newest message by date.  The
*Summary* buffer is sorted by the most recent date in each thread.

This seems like it should be simple: Set
`gnus-sort-gathered-threads-function' to `gnus-thread-sort-by-date', and
set `gnus-thread-sort-functions' to
`gnus-thread-sort-by-most-recent-date'.  (Well, I lie a little.  I
actually want the reverse of `gnus-thread-sort-by-most-recent-date',
putting the oldest threads at the top, but that's easy to hack.)

But this doesn't seem to do what I want.  It looks like Gnus makes
threads, sorts them, gathers the threads, and then sorts within the
threads.  The upshot is my threads get gathered correctly, and the
messages in a thread are sorted correctly, but the threads are sorted by
(I believe accident) the oldest message in each thread, rather than the
most recent.

Am I doing something wrong?  Is there another way to achieve my desired
result?

-- 
Michael Welsh Duggan
(md5i@md5i.com)