For build 1542 cbtransfer still need the -x try_xwm=0 flag

I have 2 nodes installed with 2.0.0-1542 build. I create 1K items in default bucket in one node. I try to use cbtransfer to recover the data to another node.
So the source is couchstore file and the destination is couchbase server http://HOST:PORT

[chisheng@cen-1716 ~]$ cd /opt/couchbase/bin/tools/
[chisheng@cen-1716 tools]$ ./cbtransfer couchstore-files:///opt/couchbase/var/lib/couchbase/data/ http://Administrator:password@10.5.2.23:8091 -b default -B default
2012-08-06 16:18:23,351: s0 error: async operation: error: MCSink MC error: 4 on sink: http://Administrator:password@10.5.2.23:8091(default@N/A)
error: MCSink MC error: 4

Then I add -x try_xwm=0
[chisheng@cen-1716 tools]$ ./cbtransfer couchstore-files:///opt/couchbase/var/lib/couchbase/data/ http://Administrator:password@10.5.2.23:8091 -b default -B default -x try_xwm=0
.
bucket: default, msgs transferred...
       : total | last | per sec
 batch : 1 | 1 | 3.7
 byte : 256000 | 256000 | 946199.8
 msg : 1000 | 1000 | 3696.1
Traceback (most recent call last):
  File "/opt/couchbase/lib/python/cbtransfer", line 31, in <module>
    sys.exit(pump_transfer.Transfer().main(sys.argv))
  File "/opt/couchbase/lib/python/pump_transfer.py", line 78, in main
    sink_class, sink).run()
  File "/opt/couchbase/lib/python/pump.py", line 125, in run
    rv = self.transfer_bucket_design(source_bucket, source_map, sink_map)
  File "/opt/couchbase/lib/python/pump.py", line 242, in transfer_bucket_design
    source_design)
  File "/opt/couchbase/lib/python/pump_cb.py", line 150, in consume_design
    id = row['id']
TypeError: string indices must be integers.

The recovery succeeds and all 1K items are recovered in another node. But there is a TypeError msg.