dovecot - Jul 2014 - Panic: file mail-index.c: line 650 (mail_index_close): assertion failed: (index->open_count > 0)

Hello,

I'm use the virtual plugin for list all unread messages in the public 
namespace.
Every time the connection is terminated with this error message when I 
select the virtual/projekte mailbox. Do not show any emails.

The version is build today from source 2.2.13.auto+102

Hardy

*** dovecot-virtual ***
!INBOX
Projekte/*
   unseen
**********************


*** part of dovecot -n ***
# 2.2.13 (fd0616d553b0): /etc/dovecot/dovecot.conf
# OS: Linux 3.2.0-4-amd64 x86_64 Debian 7.5 ext4

namespace {
   list = children
   location = mdbox:/var/mail/projekte/:INDEXPVT=/var/mail/user/%n/projekte
   prefix = Projekte/
   separator = /
   subscriptions = no
   type = public
}
*************************

GNU gdb (GDB) 7.4.1-debian
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later 
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show
copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /usr/lib/dovecot/imap...(no debugging symbols 
found)...done.
Attaching to program: /usr/lib/dovecot/imap, process 6839
ptrace: Kein passender Prozess gefunden.
[New LWP 6839]

warning: Can't read pathname for load map: Eingabe-/Ausgabefehler.
[Thread debugging using libthread_db enabled]
Using host libthread_db library
"/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `dovecot/imap imap-postlogin'.
Program terminated with signal 6, Aborted.
#0  0x00007f38fc37c475 in raise () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt full
#0  0x00007f38fc37c475 in raise () from /lib/x86_64-linux-gnu/libc.so.6
No symbol table info available.
#1  0x00007f38fc37f6f0 in abort () from /lib/x86_64-linux-gnu/libc.so.6
No symbol table info available.
#2  0x00007f38fc742395 in ?? () from /usr/lib/dovecot/libdovecot.so.0
No symbol table info available.
#3  0x00007f38fc7423fe in ?? () from /usr/lib/dovecot/libdovecot.so.0
No symbol table info available.
#4  0x00007f38fc6fa96e in i_panic () from /usr/lib/dovecot/libdovecot.so.0
No symbol table info available.
#5  0x00007f38fca6a1e1 in mail_index_close () from 
/usr/lib/dovecot/libdovecot-storage.so.0
No symbol table info available.
#6  0x00007f38fca5c46c in index_storage_mailbox_close () from 
/usr/lib/dovecot/libdovecot-storage.so.0
No symbol table info available.
#7  0x00007f38fca2fb8d in mailbox_close () from 
/usr/lib/dovecot/libdovecot-storage.so.0
No symbol table info available.
#8  0x00007f38fb0f600d in ?? () from 
/usr/lib/dovecot/modules/lib20_virtual_plugin.so
No symbol table info available.
#9  0x00007f38fb0f61b0 in virtual_backend_box_open () from 
/usr/lib/dovecot/modules/lib20_virtual_plugin.so
No symbol table info available.
#10 0x00007f38fb0f7860 in virtual_storage_sync_init () from 
/usr/lib/dovecot/modules/lib20_virtual_plugin.so
No symbol table info available.
#11 0x00007f38fca30703 in mailbox_sync_init () from 
/usr/lib/dovecot/libdovecot-storage.so.0
No symbol table info available.
#12 0x00007f38fca30827 in mailbox_sync () from 
/usr/lib/dovecot/libdovecot-storage.so.0
No symbol table info available.
#13 0x00007f38fca5afd0 in index_storage_get_status () from 
/usr/lib/dovecot/libdovecot-storage.so.0
No symbol table info available.
#14 0x00007f38fb0f5458 in ?? () from 
/usr/lib/dovecot/modules/lib20_virtual_plugin.so
No symbol table info available.
#15 0x00007f38fbb1b794 in ?? () from 
/usr/lib/dovecot/modules/lib01_acl_plugin.so
No symbol table info available.
#16 0x00007f38fca31a30 in mailbox_get_status () from 
/usr/lib/dovecot/libdovecot-storage.so.0
No symbol table info available.
#17 0x000000000041eb4b in imap_status_get ()
No symbol table info available.
#18 0x0000000000414329 in cmd_status ()
No symbol table info available.
#19 0x000000000041849c in command_exec ()
No symbol table info available.
#20 0x00000000004174e0 in ?? ()
No symbol table info available.
#21 0x0000000000417574 in ?? ()
No symbol table info available.
---Type <return> to continue, or q <return> to quit---
#22 0x0000000000417855 in client_handle_input ()
No symbol table info available.
#23 0x0000000000417c02 in client_input ()
No symbol table info available.
#24 0x00007f38fc7538be in io_loop_call_io () from 
/usr/lib/dovecot/libdovecot.so.0
No symbol table info available.
#25 0x00007f38fc7548cb in io_loop_handler_run_internal () from 
/usr/lib/dovecot/libdovecot.so.0
No symbol table info available.
#26 0x00007f38fc753949 in io_loop_handler_run () from 
/usr/lib/dovecot/libdovecot.so.0
No symbol table info available.
#27 0x00007f38fc7539c8 in io_loop_run () from 
/usr/lib/dovecot/libdovecot.so.0
No symbol table info available.
#28 0x00007f38fc6ffe13 in master_service_run () from 
/usr/lib/dovecot/libdovecot.so.0
No symbol table info available.
#29 0x000000000040c238 in main ()
No symbol table info available.
(gdb)