MB-8890 Fix to the incorrect check for deleted/non-existent items

Change-Id: I3669419ba83b6624e58d9feebc0f695ca6212824
Reviewed-on: http://review.couchbase.org/28428
Reviewed-by: Sundararaman Sridharan <sundar.sridharan@gmail.com>
Tested-by: Chiyoung Seo <chiyoung.seo@gmail.com>