Make it possible to import Jedi in Python 2 again.

jedi/evaluate/compiled/fake.py

@@ -22,21 +22,25 @@ MethodDescriptorType = type(str.replace)
 NOT_CLASS_TYPES = (
     types.BuiltinFunctionType,
     types.CodeType,
-    types.DynamicClassAttribute,
     types.FrameType,
     types.FunctionType,
     types.GeneratorType,
     types.GetSetDescriptorType,
     types.LambdaType,
-    types.MappingProxyType,
     types.MemberDescriptorType,
     types.MethodType,
     types.ModuleType,
-    types.SimpleNamespace,
     types.TracebackType,
     MethodDescriptorType
 )
 
+if is_py3:
+    NOT_CLASS_TYPES += (
+        types.DynamicClassAttribute,
+        types.MappingProxyType,
+        types.SimpleNamespace
+    )
+
 
 def _load_faked_module(module):
     module_name = module.__name__