.

wcfs/internal/xbtree/δbtail.go

@@ -846,8 +846,6 @@ func (δBtail *ΔBtail) SliceByRootRev(root zodb.Oid, lo, hi zodb.Tid) /*readonl
 	if !ok {
 		return []ΔTree{}
 	}
-	// XXX dup data - because they can be further rebuilt in parallel to caller using them
-	// XXX no -> dup data in rebuild, not here
 
 	vδT := δTtail.vδT
 	l := len(vδT)
@@ -867,6 +865,10 @@ func (δBtail *ΔBtail) SliceByRootRev(root zodb.Oid, lo, hi zodb.Tid) /*readonl
 	for ; i >= 0 && vδT[i].Rev > lo; i-- {}
         i++
 
+	// NOTE: no need to duplicate returned vδT slice because
+	// _ΔTtail.rebuild clones vδT before modifying it. This way the data we
+	// return to caller will stay unchanged even if rebuild is running
+	// simulataneously.
 	return vδT[i:j+1]
 }