Fixes #1150: Error when uploading image attachments with Unicode names under Python 2

netbox/extras/models.py

@@ -383,7 +383,7 @@ def image_upload(instance, filename):
     elif instance.name:
         filename = instance.name
 
-    return '{}{}_{}_{}'.format(path, instance.content_type.name, instance.object_id, filename)
+    return u'{}{}_{}_{}'.format(path, instance.content_type.name, instance.object_id, filename)
 
 
 @python_2_unicode_compatible