The JCR TCK test org.apache.jackrabbit.test.api.query.qom.ColumnTest#testExpandColumnsForNodeType method performs this query:

SELECT s.* FROM [nt:unstructured] AS s

and then attempts to check that the results include columns for each non-residual and single-valued property definition. "jcr:primaryType" is one such single-valued and non-residual property definition, but the test expects the column name to include the source and be named "s.jcr:primaryType" even though the query includes just a single source.

(This was not found earlier because the test was excluded due to JCR-3313; see MODE-1396.