Graceful Failover when one node joined cluster : Rebalance exited with reason {vbmap_error, <<"panic: chain refers to tag or node with zero count\n\ngoroutine 1

steps:
1. 2 nodes in cluster: 10.3.4.144, 10.3.4.146
2. Node ns_1@10.3.4.145 joined cluster
3. Starting vbucket moves for graceful failover of 'ns_1@10.3.4.144'
4. Failed over 'ns_1@10.3.4.144': ok
5. add 10.3.4.144 back
5. Starting rebalance, KeepNodes = ['ns_1@10.3.4.146','ns_1@10.3.4.145',
'ns_1@10.3.4.144'], EjectNodes = []

Rebalance exited with reason

{vbmap_error, <<"panic: chain refers to tag or node with zero count\n\ngoroutine 1 [running]:\nruntime.panic(0x8128340, 0x18654e68)\n\t/usr/lib/go/src/pkg/runtime/panic.c:266 +0xac\nmain.(*selectionCtx).noteChain(0x1862f680, 0x18654e60, 0x1, 0x1)\n\t/home/shaleny/dev/membase/repo30/ns_server/deps/vbmap/vbmap.go:211 +0x23b\nmain.buildVbmap(0x1864bae0, 0x3, 0x3, 0x186448c0, 0x3, ...)\n\t/home/shaleny/dev/membase/repo30/ns_server/deps/vbmap/vbmap.go:496 +0x504\nmain.VbmapGenerate(0x1861b4a0, 0x3, 0x1, 0x400, 0x1, ...)\n\t/home/shaleny/dev/membase/repo30/ns_server/deps/vbmap/vbmap.go:626 +0x3e3\nmain.main()\n\t/home/shaleny/dev/membase/repo30/ns_server/deps/vbmap/main.go:346 +0xeef\n">>}

ns_orchestrator002 ns_1@10.3.4.144 10:16:08 - Mon Mar 17, 2014
Bucket "d" loaded on node 'ns_1@10.3.4.145' in 0 seconds. ns_memcached000 ns_1@10.3.4.145 10:16:08 - Mon Mar 17, 2014
Bucket "d" loaded on node 'ns_1@10.3.4.144' in 0 seconds. ns_memcached000 ns_1@10.3.4.144 10:16:08 - Mon Mar 17, 2014
Started rebalancing bucket d ns_rebalancer000 ns_1@10.3.4.144 10:16:07 - Mon Mar 17, 2014
Deleting old data files of bucket "d" ns_storage_conf000 ns_1@10.3.4.144 10:16:03 - Mon Mar 17, 2014
Starting rebalance, KeepNodes = ['ns_1@10.3.4.146','ns_1@10.3.4.145',
'ns_1@10.3.4.144'], EjectNodes = []
ns_orchestrator004 ns_1@10.3.4.144 10:16:03 - Mon Mar 17, 2014
Shutting down bucket "d" on 'ns_1@10.3.4.144' for deletion ns_memcached000 ns_1@10.3.4.144 10:14:28 - Mon Mar 17, 2014
Failed over 'ns_1@10.3.4.144': ok ns_rebalancer000 ns_1@10.3.4.144 10:14:28 - Mon Mar 17, 2014
Starting failing over 'ns_1@10.3.4.144' ns_rebalancer000 ns_1@10.3.4.144 10:14:27 - Mon Mar 17, 2014
Bucket "d" rebalance appears to be swap rebalance ns_vbucket_mover000 ns_1@10.3.4.144 10:11:00 - Mon Mar 17, 2014
Starting vbucket moves for graceful failover of 'ns_1@10.3.4.144' ns_rebalancer000 ns_1@10.3.4.144 10:11:00 - Mon Mar 17, 2014
Node ns_1@10.3.4.145 joined cluster ns_cluster003 ns_1@10.3.4.145 10:10:52 - Mon Mar 17, 2014