fix RebalanceWithXdcrTest when no rebalance
fix RebalanceWithXdcrTest when no rebalance

Change-Id: Icdbc84e180545a8728e37b40936c7b9fd1dd9031
Reviewed-on: http://review.couchbase.org/65105
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Andrei Baranouski <f6b50d8f3f8d6abadc89468769320bb7ef9099f0@gmail.com>

couchbase/perfrunner,couchbase/perfrunner,EricACooper/perfrunner,pavel-paulau/perfrunner,couchbase/perfrunner,pavel-paulau/perfrunner,pavel-paulau/perfrunner,EricACooper/perfrunner,couchbase/perfrunner,pavel-paulau/perfrunner,couchbase/perfrunner,EricACooper/perfrunner,pavel-paulau/perfrunner,EricACooper/perfrunner,couchbase/perfrunner