{UPR}:: Rebalance-in hangs with 2 nodes

3.0.0-828

centos 64 bit, 6x,10.5.2.13, 10.5.2.14

1. Add 1 node to cluster 10.5.2.13
2. Create default bucket
3. Add 1K items
4. Rebalance-in 1 node 10.5.2.14

Step 4 leads to rebalance stuck

Test Run:
/testrunner -i /tmp/centos-64-2.0-basic-rebalance-tests-P0.ini get-cbcollect-info=False,verify_unacked_bytes=True -t rebalance.rebalancein.RebalanceInTests.rebalance_in_with_warming_up,GROUP=IN;BASIC;P1,BUGS=MB-7660_curr_items_tot_vb_replica_curr_items_mismatch_mixed_cluster_with_warming_up

http://qa.hq.northscale.net/job/centos_x64--02_04--Rebalance_tests_UPR-P0/251/