packet seems lost when I use NewDecodingLayerParser

[c625473164]

Its ok when I write code like this.

packet := gopacket.NewPacket(data, layers.LayerTypeEthernet, gopacket.Default)
			if packet.NetworkLayer() == nil || packet.TransportLayer() == nil || packet.TransportLayer().LayerType() != layers.LayerTypeTCP {
				continue
			}
			tcp, ok := packet.TransportLayer().(*layers.TCP)
			if !ok {
				continue
			}
			assembler.assemble(packet.NetworkLayer().NetworkFlow(), tcp, packet.Metadata().Timestamp)