Jython StringTemplate un(shallow)copyable

I've started porting to Jython a Python application, which uses the Python version of StringTemplate. Right after the start I've bumped into an error when using StringTemplateGroup.
The Python code looks like this:

def go():
   g = stringtemplate.StringTemplateGroup("A","B")
   g.getInstanceOf("A_TEMPLATE")

When calling go() from Java/Jython, the following exception is raised:

Exception in thread "main" Traceback (innermost last):
  ...
  ...
  File "C:\DEV\stringtemplate3\groups.py", line 363, in getInstanceOf
  File "C:\DEV\stringtemplate3\templates.py", line 391, in getInstanceOf
  File "C:\DEV\stringtemplate3\templates.py", line 369, in dup
  File "C:\DEV\jython2.2.1\Lib\copy.py", line 78, in copy
Error: un(shallow)copyable object of type 

Others have bumped into this error too. It's because Jython doesn't fully implement object copying (in the same sense that CPython doesn't implement it fully -- you cannot just copy arbitraty C objects). It turns out, that this isn't a problem for me, because as soon as I've changed the StringTemplateGroup error listener to my own (copyable) listener, the problem went away.

But there's one caveat. I actually choose to NOT use any custom error listener, because console errors are okay for me, so I've tried and put errors=None in the StringTemplateGroup constructor, which is a no-no, because None means "use the default one", which is exactly what I didn't want right now.

So the final solution was to redefine go like so:

def go():
   g = stringtemplate.StringTemplateGroup("A","B")
   g.errorListener = None
   g.getInstanceOf("A_TEMPLATE")

Works like a charm, so far.