Why does Magento remove my frontend cookie after using customer/session? - magento

Question

I'm using Nginx and HHVM, I'm also using custom php files to interact with Magento.
When I run any PHP file the frontend cookie gets set properly, also the shoppingcart works fine.
However, whenever I use:
$session = Mage::getSingleton( 'customer/session' );
$session->login($login, $pass);
$session->setCustomerAsLoggedIn($customer);
The frontend cookie gets removed.
Question: why is that and what can I do to solve it?
Settings:
Complete example:
include_once('../app/Mage.php');
ob_start();
umask(0);
Mage::app();
Mage::getSingleton('core/session', array('name'=>'frontend'));
$login = $v[0]; //username as email
$pass = $v[1]; //user password
try {
$customer = Mage::getModel("customer/customer");
$customer->website_id = Mage::app()->getWebsite()->getId();
$customer->loadByEmail($login);
$session = Mage::getSingleton( 'customer/session' );
$session->login($login, $pass);
$session->setCustomerAsLoggedIn($customer);
} catch(Exception $e) {
$returnJson['success'] = false;
$returnJson['error'] = $e;
}

Answer 1

We solved this issue by adding the HHVM ini setting:
hhvm.server.allow_duplicate_cookies = 0
More info: https://github.com/facebook/hhvm/issues/2758

Answer 2

Maybe not related, but why load the customer before even logging in, and you never check if the login function returns true or false. Also you manually set the customer as logged in, this is performed inside the login() function for you if the user/pass is correct. I would basically change the whole try..catch part to something like:
try {
$session = Mage::getSingleton( 'customer/session' );
if (!$session->login($login, $pass)) {
throw new Exception("Authentication failed");
}
$customer = $session->getCustomer();
// more stuff?
} catch(Exception $e) {
$returnJson['success'] = false;
$returnJson['error'] = $e;
}
Obviously not tested/proofread for lazy reasons. :)