Comment 1 for bug 1360151

Here is a snippet from s3.py

[s3.py]
:
:
            it = utils.chunkreadable(image_file,
                                     self.s3_store_large_object_chunk_size)

            for p in range(threads):
                chunk = next(it)
                clen = len(chunk)
                checksum.update(chunk)
                fp = six.BytesIO(chunk)
                fp.seek(0)
                part = UploadPart(mpu, fp, cstart + 1, clen)
                pool.spawn_n(run_upload, part)
                plist.append(part)
                cstart += 1