Canceled future will still call finished() even through they're canceled

[vpicaver]

In my use case, a class maybe called to do work multiple time. It's generally useful to start an processing the data, but if new data is submitted, the class restarts the processing and cancels previous runs. For example:

class TestClass {
    public:
        void doWork() {

            if(m_doWorkFuture.isRunning() || m_doWorkFuture.isStarted()) {
                m_doWorkFuture.cancel();
            }

            int currentCount = m_count;
            auto runFuture = QtConcurrent::run([currentCount](){
                return currentCount + 1;
            });

            m_doWorkFuture = runFuture;

            m_subscribeFuture = observe(runFuture).subscribe([this](){
                m_finishCount++;
            },
            [this](){
                m_cancelCount++;
            }).future();

        }

        void waitToFinish() {
            await(m_subscribeFuture);
        }

        QFuture<void> m_subscribeFuture;
        QFuture<int> m_doWorkFuture;
        int m_count = 0;
        int m_finishCount = 0;
        int m_cancelCount = 0;
    };

    TestClass myTest;
    myTest.doWork();
    myTest.doWork();
    myTest.doWork();
    myTest.waitToFinish();

    QCOMPARE(myTest.m_finishCount, 1);
    QCOMPARE(myTest.m_cancelCount, 2);`

This test currently fails on the master on windows.