Stream.concat incorrectly calculates unsized state

The concat spliterator calculates unsized state as follows:

            unsized = aSpliterator.hasCharacteristics(SIZED)
                      && aSpliterator.hasCharacteristics(SIZED)
                      && aSpliterator.estimateSize() + bSpliterator.estimateSize() < 0;

There is a typo on the second line: bSpliterator should be used instead.