Removed useless warning silencing.

import os

import pickle

import unittest

import warnings

from django.core.exceptions import SuspiciousOperation

from django.core.serializers.json import DjangoJSONEncoder

                         SimpleCookie, BadHeaderError, JsonResponse,

                         parse_cookie)

from django.test import TestCase

from django.utils.deprecation import RemovedInDjango18Warning

from django.utils.encoding import smart_str, force_text

from django.utils.functional import lazy

from django.utils._os import upath

        file1 = open(filename)

        r = HttpResponse(file1)

        self.assertFalse(file1.closed)

        with warnings.catch_warnings():

            warnings.simplefilter("ignore", RemovedInDjango18Warning)

        list(r)

        self.assertFalse(file1.closed)

        r.close()