looks like setting ExposeHeaders has no effect on requests to s3 (headers such as `x-amz-version-id` don't reach the clients) for browser-based uploads. 

http://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectPOST.html
key_by_path = 'key-by-hostname'
        
        queue_url = self.sqs_client.create_queue(QueueName=TEST_QUEUE_FOR_BUCKET_WITH_NOTIFICATION)['QueueUrl']
        queue_attributes = self.sqs_client.get_queue_attributes(QueueUrl=queue_url, AttributeNames=['QueueArn'])
        
        self.s3_client.create_bucket(Bucket=TEST_BUCKET_WITH_NOTIFICATION)
        self.s3_client.put_bucket_notification_configuration(Bucket=TEST_BUCKET_WITH_NOTIFICATION,
            NotificationConfiguration={'QueueConfigurations': [
                {'QueueArn': queue_attributes['Attributes']['QueueArn'], 'Events': ['s3:ObjectCreated:*']}]})
        
        self._perform_multipart_upload(bucket=TEST_BUCKET_WITH_NOTIFICATION, key=key_by_path, zip=True)
        queue_attributes = self.sqs_client.get_queue_attributes(
            QueueUrl=queue_url, AttributeNames=['ApproximateNumberOfMessages'])
        message_count = queue_attributes['Attributes']['ApproximateNumberOfMessages']
        
        self.assertEqual(message_count, '1')
        
        self.sqs_client.delete_queue(QueueUrl=queue_url)
        self.s3_client.delete_objects(Bucket=TEST_BUCKET_WITH_NOTIFICATION,
                                 Delete={'Objects': [{'Key': key_by_path}]})
        self.s3_client.delete_bucket(Bucket=TEST_BUCKET_WITH_NOTIFICATION)
    def test_s3_get_response_default_content_type(self):