.

wcfs/internal/zdata/δftail.go

@@ -575,7 +575,10 @@ func diffF(ctx context.Context, a, b *ZBigFile) (δ *_ΔZBigFile, err error) {
 		δ.blktabNew  = b.blktab.POid()
 	}
 
-	// XXX return δ=nil if no change?
+	// return δ=nil if no change
+	if δ.blksizeOld == δ.blksizeNew && δ.blktabOld == δ.blktabNew {
+		δ = nil
+	}
 	return δ, nil
 }