MB-11775: anticipate rebalance stop while verifying replicas
MB-11775: anticipate rebalance stop while verifying replicas

This merges reverted commit back.

Change-Id: I9fd370e59562b8e8a07a1ef383c442ccf4b7fd1e
Reviewed-on: http://review.couchbase.org/39756
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Reviewed-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>

ceejatec/ns_server,mschoch/ns_server,membase/ns_server,nimishzynga/ns_server,mschoch/ns_server,mschoch/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,mschoch/ns_server,nimishzynga/ns_server,membase/ns_server,nimishzynga/ns_server,membase/ns_server,membase/ns_server,t3rm1n4l/ns_server,nimishzynga/ns_server,mschoch/ns_server,nimishzynga/ns_server,membase/ns_server,ceejatec/ns_server,t3rm1n4l/ns_server,mschoch/ns_server,nimishzynga/ns_server,ceejatec/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,t3rm1n4l/ns_server,membase/ns_server,ceejatec/ns_server