BUTLER, Pa. — Former President Donald Trump plans to return Saturday to the site where a gunman tried to assassinate him in July, setting aside what are now near-constant worries for his physical safety in order to fulfill a promise — “really an obligation,” he said recently — to the people of Butler, Pennsylvania. [time-brightcove not-tgx=”true”] “I’ll probably start off by saying, ‘As I was saying …’” the Republican presidential nominee has joked, in a bit of black humor about a speech cut short when a bullet struck Trump’s ear and he was whisked off stage — fist aloft — with blood dripping across his face. Trump’s running mate, Ohio Sen.