Description:
------------
When trying to insert a file the MongoId isn't returned. Instead it returns empty despite the file being actually saved.

This happened after updating from Pecl Mongo 1.0.11 to 1.2.9. After reading the release notes of several releases I decided to downgrade to 1.2.4 and the script behaved as expected.

Test script:
---------------
$result = $this->getCollection()->put($filename, $rawData);
if($result !== false)
{
  //do something
}


Expected result:
----------------
Should return MongoId as per docs.

Actual result:
--------------
Returns empty