Is NetworkConnection.SendBytes broken?

public bool SendBytes(byte[] bytes, int numBytes, int channelId);
Parameters
bytes The array of data to be sent.
numBytes The number of bytes in the array to be sent.
channelId The transport channel to send on.

At lest while testing on host mode in 2017.2.0f2 it seems to ignore numBytes and send the length of the byte buffer array.

//send 20 bytes
Len[20],16,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
//receive
Debug.LogFormat("read {0}/{1}", read.Position, read.Length);
read 4/512
//buffer
Buffer = new byte[512];