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
if isinstance(to_str(lifecycle), six.string_types):
        lifecycle = xmltodict.parse(lifecycle)
    BUCKET_LIFECYCLE[bucket_name] = lifecycle
    response = Response()
    response.status_code = 200
    return response
def strip_chunk_signatures(data):
    
    
    #
    
    
    
    data_new = re.sub(b'(\r\n)?[0-9a-fA-F]+;chunk-signature=[0-9a-f]{64}(\r\n){,2}', b'',
        data, flags=re.MULTILINE | re.DOTALL)
    if data_new != data:
        
        for i in range(0, 2):
            if len(data_new) and data_new[0] in (10, 13):
                data_new = data_new[1:]
        for i in range(0, 6):
            if len(data_new) and data_new[-1] in (10, 13):
                data_new = data_new[:-1]
    return data_new
def bucket_exists(bucket_name):