rsync hangs during --remove-source-files

[Thomas Gutzler]

Hi,

I'm using the following command to move files from a to b:
rsync -avvvv --remove-source-files --ignore-existing /path/to/dir1/
/path/to/dir2 >> logfile
dir2 isn't empty so I only move files from dir1 to dir2 that don't exist
already.
Every so often rsync stops in the middle and doesn't continue with the
result that I have to kill it.

The last time it happened, rsync had successfully moved 1320 files,
there were 2943 files in dir2 and 1101 files in dir1.
lsof showed no open files inside dir1 or dir2, the log file was opened 4
times, dir1 itself showed up and dir2 twice. This is on a dual core CPU
with rsync version 3.0.4  protocol version 30.

The log file shows no errors. Last 4 lines say:
renaming dir/res/.svn/text-base/.somefile.svn-base.mDBdUb to
dir/res/.svn/text-base/somefile.svn-base
sender removed dir/.svn/text-base/somefile.svn-base
touch_up_dirs: dir/.svn/prop-base (84)
set modtime of dir/res/.svn/prop-base to (1223212308) Sun Oct  5
21:11:48 2008

Any suggestions how to debug this so that I can find out what's going
on? Unfortunately I haven't found a way to reproduce it. Every time I
kill and execute the same command again, it works.

Cheers,
  Tom