MB-9942: Only request updates when needed

If the end sequence is the same as the current sequence,
no updates are needed.

Change-Id: I2522be15f193371f6d96b3baedf3acfc0e2986e2
Reviewed-on: http://review.couchbase.org/32596
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>
Tested-by: buildbot <build@couchbase.com>