Upgrading was less than smooth. It's a mix of Mavericks and JMockit that were the source of the trouble. If Apple had left my JVM alone, the problem wouldn't have manifested. The code would have worked due to the "miracle" that had it working before. And if JMockit wasn't so finicky, this never would have been an issue.
Really? IT needs tools.jar in the classpath on a Mac. And needs to be in the classpath before JUnit. Picky mock library.