doveadm backup -R -m -s not picking up a new message

[Daniel Shahaf]

Daniel Shahaf wrote on Thu, 06 Feb 2020 03:37 +0000:
> Good morning,
> 
> I use «doveadm backup -R -m foo -s $state» to create a local mirror of
> an imapc remote folder.  When I run that command, wait for it to finish,
> deliver a new message to the remote folder, and run that command again,
> the new message does not get downloaded from the remote.
⋮
> dsync(fmsync): Debug: brain M: Skipping mailbox $guid1 with unchanged state uidvalidity=1529153257 uidnext=24289 highestmodseq=4910711 highestpvtmodseq=0 messages=24117
⋮
> 1580957437.725211 5 STATUS "lists/zsh" (UIDNEXT UIDVALIDITY)
> 1580957437.869540 * STATUS lists/zsh (UIDNEXT 24290 UIDVALIDITY 1529153257)
> 1580957437.869540 5 OK Completed
⋮
> ]]]
> 
> So, my question is: Why doesn't «doveadm backup» sync the new message?
> (Message number 24118, UID 24289, ESMTP ID 48CjYx6xvmzWp)

I've grepped around and found two potentially relevant bits of code:

1. dsync_mailbox_tree_get_selectable() calls mailbox_get_status(…,
STATUS_UIDVALIDITY | STATUS_UIDNEXT, …) without STATUS_HIGHESTMODSEQ.

2. imapc_mailbox_get_selected_status() silently ignores the
STATUS_HIGHESTMODSEQ flag.

Could either of these be related?

(I haven't had time to do a debug build to investigate further myself.)

Cheers,

Daniel