IMAP, mark_old and new mail

[Bob Bell <b_muttdev@xxxxxxxxxxxxxxxxx>]

I've finally upgraded mutt from 1.5.11 to 1.5.13 (using the Gentoo 
ebuilds).  I've found a difference with how mutt handles IMAP folders 
with unread "old" but not "new" messages.

Starting with version 1.5.12, mutt doesn't appear able to distinguish 
between a folder with only "old" and "read" messages, and a folder that 
contains some "new" messages.  If I start mutt with two folders that 
have only "old" and "read" messages, mutt will constantly say that 
I have new messages in the other folder, no matter how many times 
I switch between the folders.  This of course makes it much more 
difficult to manage my incoming mail.

Interestingly, if when I start mutt when a folder has some "new" 
messages in it (as well "old" and "read" messages), the behavior 
actually seems to be corrected, at least for a period of time.  
I haven't nailed down the exact behavior here yet.

I'm guessing that this change in behavior is related to the following 
change by Brendan:
2005-12-16 18:18:52  Brendan Cully  <brendan@xxxxxxxxxx>  (brendan)
       * imap/command.c, imap/imap.c, imap/imap_private.h,
       imap/message.c, imap/util.c: New new mail detection code. Now we
       use UIDVALIDITY/UIDNEXT to detect whether a mailbox has been
       changed since we last saw it, rather than the more ephemeral
       RECENT flag. We also keep a cache of mailboxes we've visited or
       called STATUS on, which might eventually make for better
       information in the browser and mailbox views. Big changes,
       probably not stable. IWFM.

Might it be necessary to use RECENT here if mark_old is set?  (Just 
guessing based on some things I've read; I don't really know the IMAP 
protocol)

I MUCH prefer the old behavior, and have regressed to using 1.5.11 for 
now.  If it's acknowledged that the new behavior is incorrect but the 
reason for this change in behavior isn't clear, please let me know what 
I can do to sort it out.

A small bit about my configuration:
   Tested with mutt 1.5.11-r1 vs. 1.5.12 from Gentoo
   IMAP server is Courier 4.0.4
   Have mark_old set
   Have header_cache set
I can provide the full details if necessary.

   -- Bob