Assertion `engine' failed. during rebalance

Steps to reproduce :

rebalance fails if you remove a node from the cluster when the vbuckets are still migrated from master to replica.

test case : management/replication/test_replication_1_replica_0_1_percent

errors in the ui :

Rebalance exited with reason {badmatch,{error,closed,
[

{mc_client_binary,stats_recv,4}

,

{mc_client_binary,stats,4}

,

{ns_memcached,handle_call,3}

,

{gen_server,handle_msg,5}

,

{proc_lib,init_p_do_apply,3}

]},
{gen_server,call,
[

{'ns_memcached-ReplicationTest-d7a95d8d-9ee8-44ed-8557-21c98d1434a5', 'ns_1@10.1.1.158'}

,

{get_vbucket,342}

,
30000]}}
ns_orchestrator002 ns_1@10.1.1.158 17:24:06 - Tue Apr 12, 2011
Port server memcached on node 'ns_1@10.1.1.158' exited with status 134. Restarting. Messages: 41: FATAL: The engine does not support tap
41: FATAL: The engine does not support tap
memcached: objectregistry.cc:37: bool verifyEngine(EventuallyPersistentEngine*): Assertion `engine'