.

wcfs/internal/xbtree/δbtail.go

@@ -670,9 +670,11 @@ func (δBtail *ΔBtail) _Update1(δZ *zodb.EventCommit) (δB1 _ΔBUpdate1, err e
 
 		tracefΔBtail("\n-> root<%s>  δkv: %v  δtrack: %v  δtkeycov: %v\n", root, δT, δtrack, δtkeycov)
 
-		// XXX also needs vδT clone here?
 		δTtail := δBtail.vδTbyRoot[root] // must be there
 		if len(δT) > 0 { // an object might be resaved without change
+			// NOTE no need to clone .vδT here because we only append to it:
+			//      Even though queries return vδT aliases, append
+			//      cannot change any slice returned by query to users.
 			δTtail.vδT = append(δTtail.vδT, ΔTree{Rev: δZ.Tid, KV: δT})
 		}