Start from 2015-03-16 nightly, there are many JCK Stream tests (~ 190) start failing in corelibs jdk9 nightly testing on all platforms. It seems they all failed at checkCount() in JCK-runtime-9/tests/api/java_util/stream/GenericStreamTests.java. This seems related to JDK-8067969.

java version "1.9.0-ea"
Java(TM) SE Runtime Environment (build 1.9.0-ea-langtools-nightly-h2370-20150316-b55)

jck suite info:
JCK version: 9/b08

Tests failed at similar testcase of checkCount, count_singleElement.

Here's one example:
test api/java_util/ArrayList/Stream.html
...
Note: Testcase "count_singleElement" failed with message: Expected equal to : "1", was given: "-1"
Note: at com.sun.tck.lib.Assert.assertEquals(Assert.java:696)
Note: at javasoft.sqe.tests.api.java.util.stream.Stream.CountTests.count_singleElement(CountTests.java:65)
Note: Testcase "count_singleElement" failed with arguments [[ANY, NOT_EMPTY, NOT_EQUAL_ELEMENTS, ALL_NULLS, HAS_NULLS, SINGLE, FIRST_ELEMENT_IS_NULL, ONE_NULL, NOT_MORE_THAN_THOUSAND, NOT_MORE_THAN_TEN, NOT_MORE_THAN_THREE, NOT_MORE_THAN_FIVE, NOT_MORE_THAN_TWO, NOT_MORE_THAN_FIFTY, NOT_MORE_THAN_HUNDRED, ANY_NON_ZERO, SELECTED_FOR_ALL_TESTS, SELECTED_SPLITERATOR_TESTS, SELECTED_SORTED_TESTS, SELECTED_FLATMAP_TESTS, SELECTED_COLLECT2_TESTS, SELECTED_SUBSTREAM2_TESTS, SELECTED_ONCLOSE_TESTS, SELECTED_LIMIT_TESTS, SELECTED_XMATCH_TESTS, SELECTED_FILTER_TESTS, SELECTED_DISTINCT_TESTS, SELECTED_UNORDERED_TESTS]: [null]]
...
Note: count_singleElement: Failed. test cases: 36; all failed
Note: testcase total time, ms: 37
checkCount: Failed. test cases: 7; passed: 6; failed: 1; failed: [count_singleElement]