conditional_variable::wait unexpected behavior? - c++11

Question

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();
}