Shares of Aurora Mobile (NASDAQ:JG), a Chinese provider of "big data" solutions to mobile app developers, surged after the company announced a deal with a global maker of new energy vehicles that it didn't name. While it didn't name its new partner, it did describe it, and the description seems to match a certain California-based electric-vehicle maker whose stock has had a very good year. As of 10 a.m. EST, Aurora's shares were up about 63.3% from Monday's closing price. So what I'll say this up front: It's all a bit mysterious, which should always make investors wary. Aurora said in...