.

wcfs/δbtail.go

@@ -562,6 +562,7 @@ func (prc *rangeCover) Expand(rnode *nodeInRange) []*nodeInRange {
 		children = append(children, &nodeInRange{lo, hi_, treev[i].Child()})
 	}
 
+	// del[i]; insert(@i, children)
 	*prc = append(rc[:i], append(children, rc[i+1:]...)...)
 	return children
 }
@@ -715,11 +716,13 @@ func diffT(ctx context.Context, a, b *Tree, δZTC SetOid, trackIdx map[zodb.Oid]
 			children := av.Expand(arn)
 
 			for _, rc := range children {
+				if !δZTC.Has(rc.node.POid()) {
+					continue
+				}
+
 				switch rc.node.(type) {
 				case *Tree:
-					if δZTC.Has(rc.node.POid()) {
 					aq = append(aq, rc)
-					}
 
 				case *Bucket:
 					// XXX δ += -[k]v  -[k]ø (for tracked DEL)