EntityClientPlayerMP.java:

Code:
boolean flag = isSneaking() || GuiIngame.sneak;
    if(flag != wasSneaking)
    {
    if(flag)
    {
    sendQueue.addToSendQueue(new Packet19EntityAction(this, 1));
    } else
    {
    sendQueue.addToSendQueue(new Packet19EntityAction(this, 2));
    }
    wasSneaking = flag;
    }