When an inclusion projection preserves a leaf path, PipelineDependencyGraph::getPrevModifyingStage() attributes it to the projection rather than to the stage that actually last modified it.

E.g. in [\{$set: {'a.b.c': 1}}, \{$project: {'a.b.c.d': 1}}], the graph reports that 'a.b.c.d' was modified by the projection.