.

wcfs/δbtail.go

@@ -812,13 +812,12 @@ func diffT(ctx context.Context, A, B *Tree, δZTC SetOid, trackIdx map[zodb.Oid]
 			achildren := Av.Expand(ra)
 			for _, ac := range achildren {
 				acOid := ac.node.POid()
-				// XXX len(achildren) == 1 && acOid == Invalid  -> embedded bucket
 				_, tracked := trackIdx[acOid]
 				if !tracked {
 					continue
 				}
 
-				if !δZTC.Has(acOid) {
+				if !δZTC.Has(acOid) && /*cannot skip embedded bucket:*/acOid != zodb.InvalidOid {
 					// check B children for node with ac.oid
 					// while checking expand Bv till ac.lo and ac.hi_ point to the same node
 					// ( this does not give exact answer but should be a reasonable heuristic;