Python 3.5 abc.py bug distilled

test/simple_source/def/05_abc_class.py

@@ -0,0 +1,14 @@
+# Python3.5 bug from abc.py:
+#   stmt ::= LOAD_CLOSURE RETURN_VALUE RETURN_LAST
+#
+# And this gets ignored.
+
+# Note this is similar to 06_classbug.py but not the same.
+#  classmethod -> object
+
+class abstractclassmethod(classmethod):
+    __isabstractmethod__ = True
+
+    def __init__(self, callable):
+        callable.__isabstractmethod__ = True
+        super().__init__(callable)