Sen. Bernie Sanders (I-Vt.) hasn’t lost his ability to make Democrats mad, and once again, he has triggered an intraparty kerfuffle on social media. As we head towards the next presidential cycle, many people — on the right, the left and in the media — will be saying Democrats are in the throes of an identity crisis, a struggle for their party’s soul that will tear them apart. But they aren’t, and they won’t be. The Democratic Party screws up plenty and contains its share of idiots, but when it comes to its identity, it’s doing just fine. On Wednesday,...