py3: PythonScript: func_{code,defaults} (Python2 only) => __{code,defaults}__ (Python2/Python3).

Use the latter form that works on both. On non-PythonScript code, this is of
course not an issue but Python2 PythonScript does not have a __code__ properties
and requires a patch on Shared.DC.Scripts.Signature (applied by SlapOS recipe)
so that FuncCode() object is set to not only func_code but also __code__.

product/ERP5/Document/BusinessTemplate.py

@@ -592,8 +592,9 @@ class BaseTemplateItem(Implicit, Persistent):
         # `expression_instance` is included so as to add compatibility for
         # exporting older catalog methods which might have them as their
         # properties or in their attribute dict.
-        attr_set.update(('func_code', 'func_defaults', '_code',
-                         '_lazy_compilation', 'Python_magic',
+        attr_set.update(('func_code', '__code__',
+                         'func_defaults', '__defaults__',
+                         '_code', '_lazy_compilation', 'Python_magic',
                          'expression_instance'))
         for attr in 'errors', 'warnings', '_proxy_roles':
           if not obj.__dict__.get(attr, 1):

product/ERP5Type/tests/ERP5TypeTestCase.py

@@ -1639,7 +1639,9 @@ def optimize():
   # Delay the compilations of Python Scripts until they are really executed.
   # Python Scripts are exported without those 2 attributes:
   PythonScript.func_code = lazy_func_prop('func_code', None)
+  PythonScript.__code__ = lazy_func_prop('__code__', None)
   PythonScript.func_defaults = lazy_func_prop('func_defaults', None)
+  PythonScript.__defaults__ = lazy_func_prop('__defaults__', None)
 
   def _compile(self):
     if immediate_compilation: