I've just tried upgrading 1.0t51 to 1.0a1 and it has been........ difficult.
I've been getting logs of Sig11s and other errors, and have trouble tracking them down.
Main problem seems to be with moving / copying messages. One at a time works (mostly), multiple will coredump the imap process (not yet managed to get a proper core out though...)
I'm using imap & Maildir, maildir on NFS & Indexes on UFS, Solaris 8.
Server is postfix / procmail (delivering pre-sorted into various Maildir
folders) and Dovecot 1.0a1. Client is thunderbird on OS/X.
If I turn off mbox_copy_with_hardlinks, then instead of a coredump I get a hang and an error message:
IMAP(gnb): Maildir /home/gnb/Maildir sync: UID inserted in the middle of mailbox (3871 > 3870, file = 1125740849.23189_0.lenford:2,Saa)
This is after I've removed all the cache/index files and even all the dovecot-uid files.... I'm back on 1.0t51 for now, but could have another crack at this if there are any hints.