MB-9208 if document save fails, the doc should not appear to be 'saved'

Change-Id: I4c03924675e9aa73a6990af41f94907ddf980909
Reviewed-on: http://review.couchbase.org/29310
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>