[py3] Fixed file_storage tests.

from __future__ import unicode_literals

import os

from io import BytesIO

from io import BytesIO, UnsupportedOperation

from django.utils.encoding import smart_bytes, smart_text

from django.core.files.utils import FileProxyMixin

        if not chunk_size:

            chunk_size = self.DEFAULT_CHUNK_SIZE

        if hasattr(self, 'seek'):

        try:

            self.seek(0)

        except (AttributeError, UnsupportedOperation):

            pass

        while True:

            data = self.read(chunk_size)