Issue #14211: _PyObject_GenericSetAttrWithDict() keeps a strong reference to

the descriptor because it may be destroyed before being used, destroyed during
the update of the dict for example.

Lib/test/crashers/borrowed_ref_1.py

@@ -1,29 +0,0 @@
-"""
-_PyType_Lookup() returns a borrowed reference.
-This attacks the call in dictobject.c.
-"""
-
-class A(object):
-    pass
-
-class B(object):
-    def __del__(self):
-        print('hi')
-        del D.__missing__
-
-class D(dict):
-    class __missing__:
-        def __init__(self, *args):
-            pass
-
-
-d = D()
-a = A()
-a.cycle = a
-a.other = B()
-del a
-
-prev = None
-while 1:
-    d[5]
-    prev = (prev,)