CBQE-0: fix incremental_rebalance_in_out_with_mutation_and_deletion

Change-Id: I03b14139b74eee3080d083f0ea2ba52f81382081
Reviewed-on: http://review.couchbase.org/38667
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>