NCBC-576: Do not retry operation when unknown status is returned.

Change-Id: Ic9afeb1373d9e7804cad3c2df0521b162956326d
Reviewed-on: http://review.couchbase.org/40347
Tested-by: Jeffry Morris <jeffrymorris@gmail.com>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>