Why doesen't he "test" the elephant's present temper before shooting it?

From the text:

It was perfectly clear to me what I ought to do. I ought to walk up to within, say, twenty-five yards of the elephant and test his behavior. If he charged, I could shoot; if he took no notice of me, it would be safe to leave him until the mahout came back. But also I knew that I was going to do no such thing. I was a poor shot with a rifle and the ground was soft mud into which one would sink at every step. If the elephant charged and I missed him, I should have about as much chance as a toad under a steam-roller. But even then I was not thinking particularly of my own skin, only of the watchful yellow faces behind.