Symfony version(s) affected: 4.2.2

Description
When using the new CacheContract interface as explained at https://symfony.com/doc/current/components/cache/cache_pools.html#using-the-cache-contracts using the CacheContract::get() interface all recursive calls made to the same pool fails to save their value and are recomputed even if it's an unrelated cache key.

I do understand that the stampede protection must be disabled for recursive calls for the same key but for unrelated keys this is at least for me unexpected behavior that is hard to diagnose since the calls may not be immediate and in different services.

How to reproduce

I've made a simple test gist that demonstrates the problem at https://gist.github.com/tapetersen/cc72ce3f1aaf689bf1450684e364802f

Possible Solution
If possible only skip the recursion on same key, not all recursive calls.

Additional context
In the Snippet from the test case below I would expect the second call to not be made but to return the cached value.

function functionToCache() {
    echo '<p>Computing value to cache</p>';
    sleep(1);
    return 'value';
}
$pool->get('key1', function(\Symfony\Contracts\Cache\ItemInterface $item) use ($pool) {
    // The first call should actually call the function.
    echo '<p>' . $pool->get('key2',  'functionToCache', 0) . '</p>';
    // Second call should use the now cached value
    echo '<p>' . $pool->get('key2',  'functionToCache', 0) . '</p>';
});