Fix Invalid decision type error while plotting tree in Python (#810)
Fix Invalid decision type error while plotting tree in Python (#810)

* Fix Invalid decision type error while plotting tree in Python

* Fix Invalid decision type error while plotting tree in Python (modified = to ==)

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