Description:
------------
I understood that the Mongo drivers are adding the _id property to the given array 
if the array is given by copy. This is all good.

But the Mongo drivers are not checking if the given array is itself a copy of an 
unmodified array.

By forgetting this check, it updates the initial array and its copy.

In the given test script, if I add an unset($toInsert['fooProperty']) it works as 
expected (as the array copy is now effective and different than its origin).

Test script:
---------------
<?php
class EntityObject {
    private $arData = array();
 
    public function __construct ($initialValue) {
        $this->setProperty($initialValue);
    }
 
    public function setProperty ($value) {
        $this->arData['property'] = $value;
    }
 
    public function getProperties () {
        return $this->arData;
    }
}
$entity = new EntityObject('foo');
 
$mongoClient = new MongoClient();
$toInsert = $entity->getProperties();
$mongoClient->fooDb->fooCollection->insert($toInsert, array('fsync'=>true));
 
echo "toInsert should be updated with _id \n";
print_r($toInsert);
 
echo "private data should not be updated with _id \n";
print_r($entity->getProperties());

Expected result:
----------------
toInsert should be updated with _id 
Array
(
    [property] => foo
    [_id] => MongoId Object
        (
            [$id] => 52090a28945630cf261e34fc
        )
)
private data should not be updated with _id 
Array
(
    [property] => foo
)
 

Actual result:
--------------
toInsert should be updated with _id 
Array
(
    [property] => foo
    [_id] => MongoId Object
        (
            [$id] => 52090a28945630cf261e34fc
        )
 
)
private data should not be updated with _id 
Array
(
    [property] => foo
    [_id] => MongoId Object
        (
            [$id] => 52090a28945630cf261e34fc
        )
 
)