RxJava: RxJava 2.0.6 : New undeliverable error handling

In the release docs of 2.0.6 it is stated that

If an undeliverable exception is an instance/descendant of NullPointerException, IllegalStateException (UndeliverableException and ProtocolViolationException extend this), IllegalArgumentException, CompositeException, MissingBackpressureException or OnErrorNotImplementedException, the UndeliverableException wrapping doesn’t happen.

What is the reason for that? Also I cannot confirm this behaivor. If I understand correctly

RxJavaPlugins.setErrorHandler(throwable -> {
    if (throwable instanceof OnErrorNotImplementedException) {
        throw new RuntimeExecutionException(throwable);
    }
    Timber.e(throwable, "Error handler reported");
});

Single.fromCallable(() -> {
    throw new IllegalArgumentException();
}).subscribe(o -> Timber.d("onSuccess"));

This should not be wrapped and thus not be re-thrown. But it is.