V0.21, test error - SELECT list expression references column which is neither grouped nor aggregated

We are using dbt 0.21.0, which we just updated to. We have a basic 3-column table, gs__cte_player_draftboard, that looks like this:


There are no missing values or any oddities in this table, no arrays or structs. We are testing for duplicates via the following test:

  - name: gs__cte_player_draftboard
      - unique:
          column_name: "concat(playerId, '-', draftCompetitionId)"
      - not_null:
          column_name: "playerId"
      - not_null:
          column_name: "draftCompetitionId"

th unique test is compiling into

      count(*) as failures,
      count(*) != 0 as should_warn,
      count(*) != 0 as should_error
    from (

    concat(playerId, '-', draftCompetitionId) as unique_field,
    count(*) as n_records

from `ourproject`.`ourdataset`.`gs__cte_player_draftboard`
where concat(playerId, '-', draftCompetitionId) is not null
group by concat(playerId, '-', draftCompetitionId)
having count(*) > 1

    ) dbt_internal_test

we are getting the following error:

Database Error in test unique_gs__cte_player_draftboard_concat_playerId_draftCompetitionId_ (models/ctes/schema.yml)
  SELECT list expression references column playerId which is neither grouped nor aggregated at [12:12]
  compiled SQL at ...

This seems like a dbt 0.21 problem, because this test was not failing when we were using dbt 0.16. This is such a strange error because it is such a basic test on such a basic table… any thoughts on how we can resolve, other than changing dbt versions?

i ran the exact same test in 0.19 and the test passed successfully…