Fix broken upr unit tests due to back takeover estimates

This "+ 1" was deleted by accident in a previous patch.

Change-Id: I50fab65f80abce60b3b8c0691526cf92a9043528
Reviewed-on: http://review.couchbase.org/37566
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Chiyoung Seo <chiyoung@couchbase.com>