[system test] database compaction crashed during and after rebalance

Environment:
8 windows 2008 R2 SP1 64bit in ec2 (each server has 4 core cpu, 15GB RAM, 70GB for data and 170GB for view)

1. 10.158.47.154
2. 10.159.31.68
3. 10.158.47.189
4. 10.159.13.46
5. 10.159.31.76
6. 10.159.31.101

1. 10.158.45.173
2. 10.159.31.91

Create a 6 nodes cluster.
Create a default bucket and load 45+ million items with size from 128 to 512 bytes.
Create one doc with 2 views. Let initial index complete.
Mutate items with new size from 512 to 1024 bytes (creates/updates/gets/deletes/expirations = 10/60/20/5/5)
Query view with rate 400 queries/second
Add node 10.158.45.173 to cluster and rebalance. During rebalance, monitor data and view size.
I saw data size in node 10.158.47.189 going up to big
Change data compaction setting to 2% (force data compaction) but database size is still high.
When rebalance done, database size of node 10.158.47.189 did not go down.
I check diag log of node 10.158.47.189, I see a lot of crashed on database compaction process.

=========================CRASH REPORT=========================
crasher:
initial call: compaction_daemon:spawn_vbucket_compactor/2-fun-0/0
pid: <0.9691.327>
registered_name: []
exception error: no match of right hand side value none
in function compaction_daemon:free_space/1
in call from compaction_daemon:ensure_can_db_compact/1
in call from compaction_daemon:'spawn_vbucket_compactor/2-fun-0'/4
ancestors: [<0.9688.327>,<0.9685.327>,<0.9684.327>,compaction_daemon,
<0.6769.208>,ns_server_sup,ns_server_cluster_sup,<0.67.0>]
messages: []
links: [<0.9688.327>]
dictionary: []
trap_exit: false
status: running
heap_size: 2584
stack_size: 24
reductions: 375
neighbours:

Link to mainifest file of build 2.0.0-1967 http://builds.hq.northscale.net/latestbuilds/couchbase-server-enterprise_x86_64_2.0.0-1967-rel.setup.exe.manifest.xml
I will upload collect info soon