In MC 1.6.1, the client sends a "Plugin Message" packet along with the request server info packet, the server responds correctly in this case.
If the server does not receive the plugin packet then it sends a pre-1.3 format response (that contains no protocol version info, so old clients assume 1.3)
In MC 1.6.1, the client sends a "Plugin Message" packet along with the request server info packet, the server responds correctly in this case.
If the server does not receive the plugin packet then it sends a pre-1.3 format response (that contains no protocol version info, so old clients assume 1.3)