Stream.concat behaves like terminal operation

FULL PRODUCT VERSION :


ADDITIONAL OS VERSION INFORMATION :
MacOS Sierra

A DESCRIPTION OF THE PROBLEM :
Below is the code, if you uncomment Stream.concat then you will see that stream supplier has been called, but it should not happen because concat is not a terminal operation

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Try the code fragment

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Stream.concat should behave as intermediate operation, stream supplier should not be called
ACTUAL -
I see that both streams are being initialized even without stream usage

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
@Test
    public void testConcat() {

        Stream<Integer> stream = createLazyStream();
        // Stream<Integer> result = Stream.concat(stream, createLazyStream());

    }

    private Stream<Integer> createLazyStream() {
        return StreamSupport.stream(() -> {

            System.out.println("initializing stream");
            return IntStream.range(1,10).spliterator();

        }, Spliterator.ORDERED, false);
    }
---------- END SOURCE ----------