XXX partial reversion of 1cbe460

Author: skirpichev

Lib/test/test_class.py

@@ -449,6 +449,7 @@ def __delattr__(self, *args):
 
     def testHasAttrString(self):
         import sys
+        from test.support import import_helper
         _testlimitedcapi = import_helper.import_module('_testlimitedcapi')
 
         class A:
@@ -1013,8 +1014,11 @@ class C:
         C.a = X()
         C.a = X()
 
-    @support.nomemtest
+    @cpython_only
     def test_detach_materialized_dict_no_memory(self):
+        # Skip test if _testcapi is not available:
+        import_helper.import_module('_testcapi')
+
         code = """if 1:
             import test.support
             import _testcapi