data lost in membase bucket when click fail over

Created an attachment (id=787)
diag of node A

Install ms 1.6.0beta4-83 64bit on 2 ubuntu 9.04 64bit standalone servers.
At node A, create 4 buckets (2 memcached and 2 membase).
Load data to all buckets.
Get data back at all buckets. Work as expected.
Run a load on node A.
During load running, at node A, add node B to node A.
Rebalance.
Get data back at all buckets. Work as expected.
Shutdown node B. Click fail over and not rebance yet.
Get data back from memcached buckets. Work as expected.
Get data back from membase buckets. Data lost about 50%
http://screencast.com/t/uTHt3Qzqo
http://screencast.com/t/bhcFSRYeYaC
http://screencast.com/t/sHUoQrbMl