Most importantly, if we have a pipeline like [{$rankFusion: {input: {pipelines: {a: [\{$search: {scoreDetails: true}}]}}, scoreDetails: false}], we should not be able to access the scoreDetails populated by $search. We should be sure to test this when the stage with scoreDetails: true is first and not-first in the $rankFusion inputs since that changes if the stage goes at the top-level or underneath a $unionWith once desugared.