if !n.flag.contains(EdgeFlags::DELETED) {

        if (n.flag & EdgeFlags::df()).is_empty() {
            // Inside a file, nondeleted zombies occur when we are
            // re-introducing an alive edge (for example to solve a
            // zombie conflict), and another, unknown patch deleted
            // the context in parallel.
            //
            // For folder edges, children or parents are either on the
            // same level as this edge (i.e. to/from a basename
            // vertex), in which case the zombie nature of the file
            // will be detected at output and record time.
            //
            // Or the children or parents are at different levels,
            // which isn't a zombie conflict, since it is normal
            // commutation between folder operations.
            //
            // This justifies the EdgeFlags::df() exclusion above.

                assert!(!n.flag.contains(EdgeFlags::FOLDER));

    // Iter through deleted parents of the edge's source. Any unknown
    // edge points towards a zombie.

    // Iter through the children of the non-deleted target. Any deleted
    // parent of a child makes the child a zombie.