Symfony2 PHPUnit功能测试具有x-debug-token标头而不是X-Debug-Token

Question

I'm working on a Symfony 2.8.2 application.

Now, I want to check through the profiler if an email is sent successfully. I enabled the profiler in my config_test.yml like that

framework:
    test: ~
    session:
        storage_id: session.storage.mock_file
    profiler:
        enabled: true
        collect: false

So, I enable the profiler in my client and do the request in my phpunit functional test:

$client->enableProfiler();
$client->request($method, $path, $requestParameters, array(), $headers);
$mailCollector = $client->getProfile()->getCollector('swiftmailer');

But $client->getProfile() returns false.

I found the problem in the Symfony Profiler when at line 84 tries to get the token

if (!$token = $response->headers->get('X-Debug-Token')) {
     return false;
}
return $this->loadProfile($token);

I debugged my response and I found that has four headers and one of them is named 'x-debug-token'.

Why does my header have that name? How I can modify that header to get the Profiler?

Thanks!