The running logic of obm_built_area_assessments has changed: the completeness field is no longer calculated/written if the GHS built-up area in source_id=3 is non-zero but the OBM built-up area is zero. This leads to NULL values in the completeness field, which are read as None by Python. This MR addresses this problem and results in such cases being classified as incomplete.
Test expanded to cover this case.