The replication tests aren't run as part of the junit-core ant target (nor in any of the other relevant targets).
I suggest adding the suite such that is is run as part of the top-level ant targets for testing Derby.
Note that it would have been simpler to simply run suites.All, but the special logic for JDBC 4 code may still be relevant for some platforms (JSR169). It is also nice to get some more feedback as the test cycle proceeds. The downside of not using suites.All is that we may forget adding new suites to the ant target(s), but we're adding so few new suites that it shouldn't be much of a problem.