fix: Fix bug in boto3 with imagekit that closes files upon upload

See:
boto/boto3#929
matthewwithanm/django-imagekit#391

antropoloops/storage_backends.py

@@ -1,8 +1,38 @@
+# python
+import os
 # django
 from django.conf import settings
 # contrib
+from tempfile import SpooledTemporaryFile
 from storages.backends.s3boto3 import S3Boto3Storage
 
+
 class MediaStorage(S3Boto3Storage):
     location = settings.S3_MEDIA_FOLDER
     file_overwrite = False
+
+    """
+    https://github.com/matthewwithanm/django-imagekit/issues/391#issuecomment-275367006
+    https://github.com/boto/boto3/issues/929
+    https://github.com/matthewwithanm/django-imagekit/issues/391
+    """
+    def _save(self, name, content):
+        """
+        We create a clone of the content file as when this is passed to
+        boto3 it wrongly closes the file upon upload where as the storage
+        backend expects it to still be open
+        """
+        # Seek our content back to the start
+        content.seek(0, os.SEEK_SET)
+
+        # Create a temporary file that will write to disk after a specified
+        # size. This file will be automatically deleted when closed by
+        # boto3 or after exiting the `with` statement if the boto3 is fixed
+        with SpooledTemporaryFile() as content_autoclose:
+
+            # Write our original content into our copy that will be closed by boto3
+            content_autoclose.write(content.read())
+
+            # Upload the object which will auto close the
+            # content_autoclose instance
+            return super(MediaStorage, self)._save(name, content_autoclose)