fix #461 .
fix #461 .

microsoft/LightGBM,henry0312/LightGBM,Allardvm/LightGBM,henry0312/LightGBM,huanzhang12/LightGBM,olofer/LightGBM,Allardvm/LightGBM,Allardvm/LightGBM,Allardvm/LightGBM,microsoft/LightGBM,wxchan/LightGBM,wxchan/LightGBM,wxchan/LightGBM,Allardvm/LightGBM,Laurae2/LightGBM,olofer/LightGBM,fstonezst/LightGBM,wxchan/LightGBM,Laurae2/LightGBM,Laurae2/LightGBM,Laurae2/LightGBM,henry0312/LightGBM,huanzhang12/LightGBM,huanzhang12/LightGBM,microsoft/LightGBM,microsoft/LightGBM,olofer/LightGBM,huanzhang12/LightGBM,fstonezst/LightGBM,olofer/LightGBM,wxchan/LightGBM,microsoft/LightGBM,olofer/LightGBM,henry0312/LightGBM,fstonezst/LightGBM,huanzhang12/LightGBM,henry0312/LightGBM,fstonezst/LightGBM,fstonezst/LightGBM,Laurae2/LightGBM