[windows] errors while doing rebalance with mutations in parallel

1. Setup 6 nodes cluster and rebalance
2. Add + Update + Delete data in parallel along with step3 and step 4.
3. Remove 1 node from the cluster and rebalance.
4. Add the same node remove at step4 back to cluster and rebalance
5. Wait for the disk drain to happen and validate active and replica items for the bucket.
6. Eject 3 nodes from the cluster and rebalance.
There are errors while rebalancing for an update operation, but eventually rebalance finishes.
[2015-05-04 16:28:58,301] - [task:695] ERROR - Memcached error #7 'Not my vbucket': {"rev":19964,"name":"default","uri":"/pools/default/buckets/default?

It is likely to see this error, since the vbuckets are moved around and there mutations happening in parallel, but don’t expect this for a small set of data like 100000 documents. Also I see error with other test case that have mutations in parallel while rebalancing is going on.