progressbar AssertionError

[abbat]

  File "/usr/bin/ydcmd", line 1376, in yd_put
    yd_put_retry(options, source, target)
  File "/usr/bin/ydcmd", line 1362, in yd_put_retry
    yd_query_retry(options, method, url, None, headers, source)
  File "/usr/bin/ydcmd", line 873, in yd_query_retry
    result = opener.open(request, timeout = options.timeout)
  File "/usr/lib/python2.7/urllib2.py", line 401, in open
    response = self._open(req, data)
...
  File "/usr/lib/python2.7/httplib.py", line 996, in endheaders
    self._send_output(message_body)
  File "/usr/bin/ydcmd", line 327, in _send_output
    self.send(message_body)
  File "/usr/bin/ydcmd", line 341, in send
    self.upload(data)
  File "/usr/bin/ydcmd", line 301, in upload
    bar.update(written)
  File "/usr/lib/pymodules/python2.7/progressbar.py", line 276, in update
    assert 0 <= value <= self.maxval
AssertionError