I believe it's an Asian vine snake... a rear-fanged species pretty far removed from a corn snake. If the offspring are viable would be an interesting cross.
I saw some pics of a corn night snake cross. I don't know if the hybrids were venomous or not. Their eyes looked really weird, like a corn that turned to the dark side of the force.
It's an Elaphe prasina-an Asian rat snake, not a vine snake.