darwin still does not default to utf-8, set encoding

oml/user/models.py

@@ -437,7 +437,7 @@ class List(db.Model):
                 j['path'] = f.path
                 break
             items.append(j)
-        with open(path, 'w') as f:
+        with open(path, 'w', encoding='utf-8') as f:
             json.dump(items, f, indent=4, default=_to_json, ensure_ascii=False, sort_keys=True)
 
 class Metadata(db.Model):