fixup! roundtrip test via reference passed to aliased class method

Author: rhaschke

tests/test_class_sh_with_alias.py

@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 import pytest
+import env  # noqa: F401
 
 from pybind11_tests import class_sh_with_alias as m
 
@@ -80,7 +81,11 @@ def pass_cref(self, obj):
     [
         (m.check_roundtrip_uq_cref, "pass_uq_cref"),
         (m.check_roundtrip_lref, "pass_lref"),  # modification passed through 1:1
-        (m.check_roundtrip_cref, ""),  # modification lost (forbidden due to constness)
+        pytest.param(
+            m.check_roundtrip_cref,
+            "",  # modification lost (forbidden due to constness)
+            marks=[pytest.mark.skipif("env.PYPY")],
+        ),
     ],
 )
 def test_unique_ptr_consumer_roundtrip(f, expected):