panic error while backup mailboxes with doveadm backup

Hi there is a fix for this bug:

#doveadm -v backup -fu user mdbox: ....

dsync(user): Panic: file dsync-brain-mailbox-tree-sync.c: line 111 (dsync_brain_mailbox_tree_sync_change): assertion failed: (brain->no_backup_overwrite)
dsync(user): Error: Raw backtrace: /usr/lib/dovecot/libdovecot.so.0(+0x5e271) [0x7f60764c1271] -> /usr/lib/dovecot/libdovecot.so.0(default_fatal_handler+0x2a) [0x7f60764c12da] -> /usr/lib/dovecot/libdovecot.so.0(i_fatal+0) [0x7f607647ca9e] -> doveadm [user recv_mailbox_tree_deletes](dsync_brain_mailbox_tree_sync_change+0x442) [0x7f60770e0142] -> doveadm [user recv_mailbox_tree_deletes](dsync_brain_recv_mailbox_tree_deletes+0x11b) [0x7f60770dfc4b] -> doveadm [user recv_mailbox_tree_deletes](dsync_brain_run+0x4e3) [0x7f60770dd0b3] -> doveadm [user recv_mailbox_tree_deletes](+0x2d964) [0x7f60770da964] -> doveadm [user recv_mailbox_tree_deletes](+0x15b5b) [0x7f60770c2b5b] -> doveadm [user recv_mailbox_tree_deletes](doveadm_mail_try_run+0x26c) [0x7f60770c38ac] -> doveadm [user recv_mailbox_tree_deletes](main+0x414) [0x7f60770c26d4] -> /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf5) [0x7f60760beec5] -> doveadm [user recv_mailbox_tree_deletes](+0x15922) [0x7f60770c2922]

dovecot-core 2.2.9-1ubuntu2.1 from 14.04 LTS

the fix:
https://<email address hidden>/msg56465.html
http://hg.dovecot.org/dovecot-2.2/rev/fbc8fe46dfce

dovecot-core:
  Installiert: 1:2.2.9-1ubuntu2.1
  Installationskandidat: 1:2.2.9-1ubuntu2.1
  Versionstabelle:
 *** 1:2.2.9-1ubuntu2.1 0
        500 http://de.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu/ trusty-security/main amd64 Packages
        100 /var/lib/dpkg/status
     1:2.2.9-1ubuntu2 0
        500 http://de.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages

this is a show stopper bug because it is our main mail server

Thanks
Lars
---
AlsaDevices:
 total 0
 crw-rw---- 1 root audio 116, 1 Mai 28 09:21 seq
 crw-rw---- 1 root audio 116, 33 Mai 28 09:21 timer
AplayDevices: Error: [Errno 2] No such file or directory
ApportVersion: 2.14.1-0ubuntu3.2
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CRDA: Error: [Errno 2] No such file or directory
DistroRelease: Ubuntu 14.04
HibernationDevice: RESUME=UUID=4618df75-90fb-4d7a-854e-0e2450e346b0
InstallationDate: Installed on 2014-01-10 (160 days ago)
InstallationMedia: Ubuntu-Server 14.04 LTS "Trusty Tahr" - Alpha amd64 (20140109)
MachineType: Intel Corporation S3420GP
Package: linux (not installed)
PciMultimedia:

ProcEnviron:
 TERM=rxvt
 PATH=(custom, no user)
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
ProcFB:

ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-27-generic root=UUID=e0a0ee6f-8c04-4b0d-91e7-49b369b09cd4 ro nomdmonddf nomdmonisw
ProcVersionSignature: Ubuntu 3.13.0-27.50-generic 3.13.11
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-27-generic N/A
 linux-backports-modules-3.13.0-27-generic N/A
 linux-firmware 1.127.2
RfKill: Error: [Errno 2] No such file or directory
Tags: trusty
Uname: Linux 3.13.0-27-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups:

WifiSyslog:

_MarkForUpload: True
dmi.bios.date: 05/11/2012
dmi.bios.vendor: Intel Corp.
dmi.bios.version: S3420GP.86B.01.00.0051.051120121541
dmi.board.asset.tag: ....................
dmi.board.name: S3420GP
dmi.board.vendor: Intel Corporation
dmi.board.version: E51974-406
dmi.chassis.asset.tag: ....................
dmi.chassis.type: 17
dmi.chassis.vendor: IUF-Computer
dmi.chassis.version: ..................
dmi.modalias: dmi:bvnIntelCorp.:bvrS3420GP.86B.01.00.0051.051120121541:bd05/11/2012:svnIntelCorporation:pnS3420GP:pvr....................:rvnIntelCorporation:rnS3420GP:rvrE51974-406:cvnIUF-Computer:ct17:cvr..................:
dmi.product.name: S3420GP
dmi.product.version: ....................
dmi.sys.vendor: Intel Corporation