bpo-38588: Fix possible crashes in dict and list when calling PyObject_RichCompareBool (GH-17734)

Take strong references before calling PyObject_RichCompareBool to protect against the case
where the object dies during the call.
diff --git a/Lib/test/test_dict.py b/Lib/test/test_dict.py
index 5b51376..de483ab 100644
--- a/Lib/test/test_dict.py
+++ b/Lib/test/test_dict.py
@@ -1221,7 +1221,7 @@
         support.check_free_after_iterating(self, lambda d: iter(d.items()), dict)
 
     def test_equal_operator_modifying_operand(self):
-        # test fix for seg fault reported in issue 27945 part 3.
+        # test fix for seg fault reported in bpo-27945 part 3.
         class X():
             def __del__(self):
                 dict_b.clear()
@@ -1237,6 +1237,16 @@
         dict_b = {X(): X()}
         self.assertTrue(dict_a == dict_b)
 
+        # test fix for seg fault reported in bpo-38588 part 1.
+        class Y:
+            def __eq__(self, other):
+                dict_d.clear()
+                return True
+
+        dict_c = {0: Y()}
+        dict_d = {0: set()}
+        self.assertTrue(dict_c == dict_d)
+
     def test_fromkeys_operator_modifying_dict_operand(self):
         # test fix for seg fault reported in issue 27945 part 4a.
         class X(int):