Error in search mailbox differences

[Hubbitus]

I have tried copy IMAP folders from Dovecot server to GMail. And search software what could do it reliably. Gilles Lamiral - author of imapsync recommend me try larch. But I may constatate what perhaps there also some bugs present.

I provide 2 small reproduce examples with full message sources.

Base run command:

$ cat run
#!/bin/bash

rm -rf ~/.larch

larch \ 
        --from imaps://$( cat .account.1.host )  --from-folder test.bug_2 --from-pass $( cat .account.1.pass ) --from-user $( cat .account.1.user ) \
        --to   imaps://$( cat .account.2.host )  --to-folder   test/bug_2 --to-pass   $( cat .account.2.pass ) --to-user   $( cat .account.2.user ) \
        --all --expunge --sync-flags \
        --verbosity debug

1. First, try copy folder test.bug_1 with single message http://fpaste.org/185813/:
   1.1) first run:

[23:05:02] [debug] [<] connecting...
[23:05:02] [info] [<] connected to mail.spb.ant-inform.ru on port 993 using SSL
[23:05:02] [debug] [<] authenticating using PLAIN
[23:05:03] [debug] [<] authenticated using PLAIN
[23:05:03] [debug] [<] updating mailboxes
[23:06:29] [debug] [>] connecting...
[23:06:29] [info] [>] connected to imap.googlemail.com on port 993 using SSL
[23:06:29] [debug] [>] looks like Gmail
[23:06:29] [debug] [>] authenticating using PLAIN
[23:06:29] [debug] [>] authenticated using PLAIN
[23:06:29] [debug] [>] updating mailboxes
[23:21:22] [info] [>] creating mailbox: test/bug_1
[23:21:23] [debug] [>] updating mailboxes
[23:25:18] [info] mail.spb.ant-inform.ru/test.bug_1 -> imap.googlemail.com/test/bug_1
[23:25:18] [debug] [<] test.bug_1: getting mailbox status
[23:25:18] [debug] [<] test.bug_1: examining mailbox
[23:25:19] [info] [<] test.bug_1: fetching message headers 1 through 1...
[23:25:19] [debug] [>] test/bug_1: getting mailbox status
[23:25:19] [debug] [<] test.bug_1: peeking at message: 47d22bb80395bd9b249b8ff6dddc9fa5
[23:25:19] [info] [>] copying uid 1: admin@spb.ant-inform.ru - quota warning
[23:25:19] [debug] [>] test/bug_1: selecting mailbox
[23:25:20] [debug] [>] test/bug_1: appending message: 47d22bb80395bd9b249b8ff6dddc9fa5
[23:25:22] [debug] [<] expunging deleted messages
[23:25:22] [debug] [<] test.bug_1: selecting mailbox
[23:25:22] [debug] [<] test.bug_1: expunging deleted messages
[23:25:23] [info] [<] disconnected
[23:25:23] [info] [>] disconnected
[23:25:23] [info] 1 message(s) copied, 0 failed, 0 deleted out of 1 total
[23:25:23] [debug] performing database maintenance

What interesting - I assume it copy absolutely different message, but by log it seems correct. For exclude some caching issue I have delete ~/.larch each time as you may see in script.

1.2) subsequent run:

[23:41:36] [debug] [<] connecting...
[23:41:37] [info] [<] connected to mail.spb.ant-inform.ru on port 993 using SSL
[23:41:37] [debug] [<] authenticating using PLAIN
[23:41:37] [debug] [<] authenticated using PLAIN
[23:41:37] [debug] [<] updating mailboxes
[23:43:01] [debug] [>] connecting...
[23:43:01] [info] [>] connected to imap.googlemail.com on port 993 using SSL
[23:43:01] [debug] [>] looks like Gmail
[23:43:01] [debug] [>] authenticating using PLAIN
[23:43:01] [debug] [>] authenticated using PLAIN
[23:43:01] [debug] [>] updating mailboxes
[23:58:10] [info] mail.spb.ant-inform.ru/test.bug_1 -> imap.googlemail.com/test/bug_1
[23:58:10] [debug] [<] test.bug_1: getting mailbox status
[23:58:11] [debug] [<] test.bug_1: examining mailbox
[23:58:11] [info] [<] test.bug_1: fetching message headers 1 through 1...
[23:58:11] [debug] [>] test/bug_1: getting mailbox status
[23:58:12] [debug] [>] test/bug_1: examining mailbox
[23:58:12] [info] [>] test/bug_1: fetching message headers 1 through 1...
[23:58:12] [debug] [<] test.bug_1: peeking at message: 47d22bb80395bd9b249b8ff6dddc9fa5
[23:58:12] [info] [>] copying uid 1: admin@spb.ant-inform.ru - quota warning
[23:58:12] [debug] [>] test/bug_1: selecting mailbox
[23:58:12] [debug] [>] test/bug_1: appending message: 47d22bb80395bd9b249b8ff6dddc9fa5
[23:58:14] [debug] [<] expunging deleted messages
[23:58:15] [debug] [<] test.bug_1: selecting mailbox
[23:58:15] [debug] [<] test.bug_1: expunging deleted messages
[23:58:15] [info] [<] disconnected
[23:58:15] [info] [>] disconnected
[23:58:15] [info] 1 message(s) copied, 0 failed, 0 deleted out of 1 total
[23:58:15] [debug] performing database maintenance

That message copied again and again…

Please note I use --verbosity debug option and it give very small amount of information to understand what really happened.