CBQE-984: fix got empty error

Change-Id: Ibaa003f5a9b21cf6af3ae2de9864ef7d4b92108e
Reviewed-on: http://review.couchbase.org/24157
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>