diff --git a/src/_pytest/config/__init__.py b/src/_pytest/config/__init__.py
index 437b38853..e6de86c36 100644
--- a/src/_pytest/config/__init__.py
+++ b/src/_pytest/config/__init__.py
@@ -746,10 +746,8 @@ class Config:
         and find all the installed plugins to mark them for rewriting
         by the importhook.
         """
-        # Saving _ns so it can be used for other assertion rewriting purposes
-        # e.g. experimental assertion pass hook
-        _ns, _unknown_args = self._parser.parse_known_and_unknown_args(args)
-        mode = getattr(_ns, "assertmode", "plain")
+        ns, unknown_args = self._parser.parse_known_and_unknown_args(args)
+        mode = getattr(ns, "assertmode", "plain")
         if mode == "rewrite":
             try:
                 hook = _pytest.assertion.install_importhook(self)