Well, that's fun. I don't know if maybe Jython 2.5 behaves differently than 2.7 here, but DatasetTestUtils.equals() doesn't give you a useful result because it's not being called. Jython is invoking the base Object method, which is why you're getting referential equality behavior. I can't see any way to convince Jython to invoke the static equals method correctly. @pturmel may have some ideas?
I don't think it's a bug (the behavior of the method itself is fine) outside of perhaps a bug in Jython, but fixing it is not likely to be fun or low risk. I think your best options are to 1. script this yourself or 2. use Ignition Extensions: Ignition Extensions - Convenience utilities for advanced users