In the campy 1950 movie classic
All About Eve
, a dewy young understudy insinuates herself into the social circle of a great but aging actress. As the older performer, played unforgettably by Bette Davis, begins to realize what's up that the ingenue's real goal is to supplant her on the stage she issues a raspy warning that has become one of the immortal lines in film: "Fasten your seat belts. It's going to be a bumpy night."
A very similar scene played out this week in real-life Hollywood, a place where Democratic politics is a very...