Currently, we only use and report based on the ```dwResult``` field in the ```WINHTTP_ASYNC_RESULT``` structure. This makes it difficult to know specifically what failed when a failure occurs. It would be good to include the full structure inside the ```http_exception```.
http://msdn.microsoft.com/en-us/library/windows/desktop/aa384121(v=vs.85).aspx
http://msdn.microsoft.com/en-us/library/windows/desktop/aa384121(v=vs.85).aspx
