duplicate Mails with dsync replication

[Dennis Kuhn]

Hi!

We have some strange replication issues. Some mails are duplicated when
expunged.
This bug is quite hard to reproduce, it just happens occasionally. It
seems somehow related to sieve. When i deleted the sieve script i could
not reproduce this behavior.

Here are some logs, mjm-100010 at mydomain.com is an alias for
mjm at mydomain.com:

# Master
Jun 23 00:51:41 dobby4 dovecot: lmtp(mjm-100010 at mydomain.com): copy from
<lmtp DATA>: box=INBOX, uid=7816,
msgid=<20160623005132EE517444BB$3A04DF25DD at ABRAHAM>, size=8933
Jun 23 00:51:41 dobby4 dovecot: lmtp(mjm-100010 at mydomain.com):
4N23HaMVa1fpmQEAJEBNLA: sieve:
msgid=<20160623005132EE517444BB$3A04DF25DD at ABRAHAM>: stored mail into
mailbox 'INBOX'
Jun 23 04:52:57 dobby4 dovecot: pop3(mjm at mydomain.com): expunge:
box=INBOX, uid=7816,
msgid=<20160623005132EE517444BB$3A04DF25DD at ABRAHAM>, size=8933
Jun 23 04:52:57 dobby4 dovecot: dsync-local(mjm at mydomain.com): save:
box=INBOX, uid=7817,
msgid=<20160623005132EE517444BB$3A04DF25DD at ABRAHAM>, size=8933
Jun 23 04:55:21 dobby4 dovecot: pop3(mjm at mydomain.com): expunge:
box=INBOX, uid=7817,
msgid=<20160623005132EE517444BB$3A04DF25DD at ABRAHAM>, size=8933


# Replica
Jun 23 00:51:42 dobby5 dovecot: dsync-server(mjm-100010 at mydomain.com):
save: box=INBOX, uid=7816,
msgid=<20160623005132EE517444BB$3A04DF25DD at ABRAHAM>, size=8933
Jun 23 04:52:57 dobby5 dovecot: dsync-server(mjm at mydomain.com): copy
from INBOX: box=INBOX, uid=7817,
msgid=<20160623005132EE517444BB$3A04DF25DD at ABRAHAM>, size=8933
Jun 23 04:52:57 dobby5 dovecot: dsync-server(mjm at mydomain.com): expunge:
box=INBOX, uid=7816,
msgid=<20160623005132EE517444BB$3A04DF25DD at ABRAHAM>, size=8933
Jun 23 04:55:22 dobby5 dovecot: dsync-server(mjm at mydomain.com): expunge:
box=INBOX, uid=7817,
msgid=<20160623005132EE517444BB$3A04DF25DD at ABRAHAM>, size=8933


The problem is the "dsync-server(mjm at mydomain.com): copy from INBOX:
box=INBOX, uid=7817" on dobby5 at 04:52:57.
This creates a new uid 7817 and the new mail is replicated back to
dobby4. But i have no idea what triggers this copy.

Any ideas?

The dovecot version is 2.2.24.

Thanks
Dennis