fix typo in registrar no bucket set

core/registrar.py

@@ -204,8 +204,8 @@ def registrar(
     metadata_package, data_package = None, None
     if not upload_container:
         # assuming objects_prefix = bucket/itemname
-        upload_container = objects_prefix.split("/")[0]
-        objects_prefix = objects_prefix.split("/")[1]
+        upload_container = objects_prefix.partition("/")[0]
+        objects_prefix = objects_prefix.partition("/")[2]
     with SwiftService() as swift:
         list_parts_gen = swift.list(
             container=upload_container, options={"prefix": objects_prefix},