[N1QL] test_unnest_covering_array_index fails:Difference in results seen while using a particular index.

Query issued:
SELECT t.email, r.`name` FROM default t UNNEST t.VMs AS r WHERE r.`name` = "vm_12"

Indexes created:
CREATE INDEX `idx4` ON `default`((all (array (`r`.`name`) for `r` in `VMs` end)),`email`)
CREATE INDEX `by_VMs2` ON `default`((distinct (array (`r`.`name`) for `r` in `VMs` end)),`VMs`,`email`)

The query gives different results when it used idx4 vs by_VMs2.
This test has passed before .

Assert which fails:
https://github.com/couchbase/testrunner/blob/master/pytests/tuqquery/tuq_index.py#L206