UpdateTest writes the fields the patch carries and leaves the rest alone. The testset is one of them, so carrying another one moves the test; the testset in the alternative path is not read. Pointing the input or answer at a generator makes the data regenerate asynchronously, putting the test back into pending status. The example overrides change only what the statement displays, which is what interactive problems need when the stored input and answer are instructions for the interactor rather than real data; unset_example_input and unset_example_answer drop them, since an absent oneof means the field was not carried.