Eliminate references to django.utils.six.BytesIO

wagtail/wagtailimages/models.py

@@ -4,6 +4,7 @@ import hashlib
 import os.path
 from collections import OrderedDict
 from contextlib import contextmanager
+from io import BytesIO
 
 from django.conf import settings
 from django.core import checks
@@ -14,7 +15,6 @@ from django.forms.utils import flatatt
 from django.urls import reverse
 from django.utils.functional import cached_property
 from django.utils.safestring import mark_safe
-from django.utils.six import BytesIO
 from django.utils.translation import ugettext_lazy as _
 from taggit.managers import TaggableManager
 from unidecode import unidecode

wagtail/wagtailimages/tests/test_image_operations.py

@@ -1,7 +1,8 @@
 from __future__ import absolute_import, unicode_literals
 
+from io import BytesIO
+
 from django.test import TestCase, override_settings
-from django.utils.six import BytesIO
 from mock import Mock, patch
 
 from wagtail.wagtailcore import hooks

wagtail/wagtailimages/tests/utils.py

@@ -1,8 +1,9 @@
 from __future__ import absolute_import, unicode_literals
 
+from io import BytesIO
+
 import PIL.Image
 from django.core.files.images import ImageFile
-from django.utils.six import BytesIO
 
 from wagtail.wagtailimages import get_image_model