liveins are dumped in many of the test cases and so storing them in a set can result in non-deterministic failures. I'm not sure whether this could cause of issues too... I'm also wondering how this hasn't come up before, have I missed something? SparseSet has now been replaced with a SetVector.
SpareSet is deterministic given the same input order - similar to SetVector. Printing the result is not the common use case, so changing the print function to sort the output first might be more useful for testing purposes.