rsync with --copy-devices patch and device-target with --write-batch doesnt work

[Freisei]

Hi List!

I want to use rsync to create differential backups of my lvm-snapshots.

fullbackup-filename: /mnt/sdc1/snapshotvergleich/rootbackup1.img
current snapshot: /dev/vg0/rootbackup

note: compiled-in --copy-devices-patch


root at xp8main3:/usr/local/src/rsync# ./rsync --version
rsync  version 3.1.0dev  protocol version 31.PR5
Copyright (C) 1996-2009 by Andrew Tridgell, Wayne Davison, and others.
Web site: http://rsync.samba.org/
Capabilities:
    64-bit files, 64-bit inums, 64-bit timestamps, 64-bit long ints,
    socketpairs, hardlinks, symlinks, IPv6, batchfiles, inplace,
    append, no ACLs, xattrs, iconv, symtimes

rsync comes with ABSOLUTELY NO WARRANTY.  This is free software, and you
are welcome to redistribute it under certain conditions.  See the GNU
General Public Licence for details.
root at xp8main3:/usr/local/src/rsync# ./rsync -v --progress  
--write-batch=/mnt/testvol/diff1_2_usb_copydiff 
/mnt/sdc1/snapshotvergleich/rootbackup1.img /dev/vg0/rootbackup
rootbackup1.img
     53,116,928   0%   50.62MB/s    0:03:26
rsync error: error in file IO (code 11) at io.c(1565) [sender=3.1.0dev]
root at xp8main3:/usr/local/src/rsync#

proberly more informative:
root at xp8main3:/usr/local/src/rsync# ./rsync -vvv -debug --progress  
--write-batch=/mnt/testvol/diff1_2_usb_copy          diff 
/mnt/sdc1/snapshotvergleich/rootbackup1.img /dev/vg0/rootbackup
server_recv(2) starting pid=13264
building file list ...
[sender] make_file(rootbackup1.img,*,0)
1 file to consider
send_file_list done
send_files starting
recv_file_name(rootbackup1.img)
received 1 names
recv_file_list done
get_local_name count=1 /dev/vg0/rootbackup
generator starting pid=13264
delta-transmission enabled
recv_generator(rootbackup,0)
recv_files(1) starting
send_files(0, /mnt/sdc1/snapshotvergleich/rootbackup1.img)
send_files mapped /mnt/sdc1/snapshotvergleich/rootbackup1.img of size 
10737418240
calling match_sums /mnt/sdc1/snapshotvergleich/rootbackup1.img
rootbackup1.img
     49,577,984   0%   47.25MB/s    0:03:40
rsync error: error in file IO (code 11) at io.c(1565) [sender=3.1.0dev]
_exit_cleanup(code=11, file=io.c, line=1565): about to call exit(11)