rebalance fails with bucket_engine error : bucket_engine.c:1876: bucket_engine_release_cookie: Assertion `peh' failed

rebalance is failing on the latest v0.0.0. 132 builds with these error messages :

error messages:

Port server memcached on node 'ns_1@10.1.5.228' exited with status 134. Restarting. Messages: memcached: bucket_engine.c:1876: bucket_engine_release_cookie: Assertion `peh' failed

Rebalance exited with reason {{{badmatch,{error,closed}},
[{mc_client_binary,cmd_binary_vocal_recv,5},
{mc_client_binary,get_vbucket,2},
{ns_memcached,handle_call,3},
{gen_server,handle_msg,5},
{proc_lib,init_p_do_apply,3}]},
{gen_server,call,
[{'ns_memcached-default','ns_1@10.1.5.228'},
{get_vbucket,512},
30000]}}
ns_orchestrator002 ns_1@10.1.5.227 11:23:55 - Tue Apr 12, 2011
Control connection to memcached on 'ns_1@10.1.5.228' disconnected: {{badmatch,
{error,
closed}},
[{mc_client_binary,
cmd_binary_vocal_recv,
5},
{mc_client_binary,
get_vbucket,
2},
{ns_memcached,
handle_call,
3},
{gen_server,
handle_msg,
5},
{proc_lib,
init_p_do_apply,




steps to reproduce :

1- install
2- create bucket 'default'
3- add node X
4- rebalance
5- remove X
6- rebalance

rebalance fails in step 4 and step 6