[1.8.x] Sorted imports with isort; refs #23860.

Backport of 0ed7d15563 from master

tests/staticfiles_tests/storage.py

@@ -1,6 +1,7 @@
 from datetime import datetime
-from django.core.files import storage
+
 from django.contrib.staticfiles.storage import CachedStaticFilesStorage
+from django.core.files import storage
 
 
 class DummyStorage(storage.Storage):

tests/staticfiles_tests/test_liveserver.py

@@ -6,13 +6,11 @@ django.test.LiveServerTestCase.
 
 import os
 
+from django.contrib.staticfiles.testing import StaticLiveServerTestCase
 from django.core.exceptions import ImproperlyConfigured
 from django.test import modify_settings, override_settings
-from django.utils.six.moves.urllib.request import urlopen
 from django.utils._os import upath
-
-from django.contrib.staticfiles.testing import StaticLiveServerTestCase
-
+from django.utils.six.moves.urllib.request import urlopen
 
 TEST_ROOT = os.path.dirname(upath(__file__))
 TEST_SETTINGS = {

tests/staticfiles_tests/tests.py

@@ -9,23 +9,23 @@ import sys
 import tempfile
 import unittest
 
-from django.template import Context, Template
 from django.conf import settings
+from django.contrib.staticfiles import finders, storage
+from django.contrib.staticfiles.management.commands import collectstatic
+from django.contrib.staticfiles.management.commands.collectstatic import \
+    Command as CollectstaticCommand
 from django.core.cache.backends.base import BaseCache
 from django.core.exceptions import ImproperlyConfigured
 from django.core.management import call_command
+from django.template import Context, Template
 from django.test import TestCase, override_settings
+from django.utils import six
+from django.utils._os import rmtree_errorhandler, symlinks_supported, upath
 from django.utils.encoding import force_text
 from django.utils.functional import empty
-from django.utils._os import rmtree_errorhandler, upath, symlinks_supported
-from django.utils import six
-
-from django.contrib.staticfiles import finders, storage
-from django.contrib.staticfiles.management.commands import collectstatic
 
 from .storage import DummyStorage
 
-
 TEST_ROOT = os.path.dirname(upath(__file__))
 TEST_SETTINGS = {
     'DEBUG': True,
@@ -52,7 +52,6 @@ TEST_SETTINGS = {
         'staticfiles_tests.apps.no_label',
     ),
 }
-from django.contrib.staticfiles.management.commands.collectstatic import Command as CollectstaticCommand
 
 
 class BaseStaticFilesTestCase(object):