conditional_variable::wait unexpected behavior?

I picked up the code from the conditional_variable::wait reference. The reference states that :

wait causes the current thread to block until the condition variable is notified or a spurious wakeup occurs, optionally looping until some predicate is satisfied.

The link also states that the wait is equivalent to :

while (!pred()) { wait(lock); }

If that is the case, is there a reason why the following code does not work as the original code?

#include <condition_variable>
#include <iostream>
#include <mutex>
#include <thread>

std::condition_variable cv;
std::mutex cv_m; // This mutex is used for three purposes:
                 // 1) to synchronize accesses to i
                 // 2) to synchronize accesses to std::cerr
                 // 3) for the condition variable cv
int i = 0;

void waits()
{
    std::unique_lock<std::mutex> lk(cv_m);
    std::cerr << "Waiting... \n";
    cv.wait(lk, [] {std::cout << "Check Done!" << std::endl; return i == 1; });
    std::cerr << "...finished waiting. i == 1\n";
}

void signals()
{
    std::this_thread::sleep_for(std::chrono::seconds(1));
    {
        std::lock_guard<std::mutex> lk(cv_m);
        std::cerr << "Notifying...\n";
    }
    cv.notify_all();

    std::this_thread::sleep_for(std::chrono::seconds(1));

    {
        std::lock_guard<std::mutex> lk(cv_m);
        i = 1;
        std::cerr << "Notifying again...\n";
    }
    //cv.notify_all();
}

int main()
{
    std::thread t1(waits), t2(waits), t3(waits), t4(signals);
    t1.join();
    t2.join();
    t3.join();
    t4.join();
}