THIS WORKS:
public OnRaceChanged(client,oldrace,newrace)
{
    if(newrace != thisRaceID)
    {
        bMilitia[client]=false;
        War3_WeaponRestrictTo(client,thisRaceID,"");
    }
    if(newrace == thisRaceID)
    {
        if(ValidPlayer(client,true))
        {
            War3_SetMaxHP(client,150);
            War3_WeaponRestrictTo(client,thisRaceID,"weapon_p228");
            GivePlayerItem(client, "weapon_p228");
        }
    }
}





=================================================================
THIS NOT WOKS:
public OnRaceChanged(client,oldrace,newrace)
{
    if(newrace!=thisRaceID){
        War3_SetBuff(client,bFlyMode,thisRaceID,false);
        W3ResetPlayerColor(client,thisRaceID);
        War3_WeaponRestrictTo(client,thisRaceID,"");
    }
    if(newrace==thisRaceID){
        bFlying[client]=false;
        if(ValidPlayer(client,true))
        {
            War3_WeaponRestrictTo(client,thisRaceID,"weapon_knife,weapon_hegrenade");
            GivePlayerItem(client,"weapon_hegrenade");
        }
    }
}