[9fans] upas/fs to imap: removed messages sometimes regenerate

["Anthony Sorace" <anothy@gmail.com>]

I'm seeing some odd (wrong) behavior with Plan 9's upas/fs and was
wondering of others have seen it, before I start digging further. I
use upas/fs to talk to a local mailbox and two IMAP servers. The local
store and one of the IMAP servers work reliably correctly. On the
other IMAP server, upas/fs will *sometimes* get into a state where
when I remove a message, it'll re-insert itself into the tree with a
higher message number. For example, with the IMAP server dalet:

:; cd /mail/fs/dalet
:; ls
1
2
ctl
:; rm 1 2 ; ls
3
4
ctl

Messages 3&4 are the same as 1&2; nothing new's actually come in.
Other IMAP clients I've used behave properly with this server. I've
not yet identified the pattern which causes it, but it's not random.
Anyone else seen this or similar?