[antlr-interest] No '_dbg' attribute (python 3.1.3 debug)

[Red Rackham]

With Python 3.1.3 in debug mode I get a little ways in ANTLRWorks then at some 
point I get this:

Traceback (most recent call last):
...
  File "C:\SW_SVN\ScriptConverter\PgenToAntlr\antlr\ITPParser.py", line 124821, 
in specialStateTransition
    self_.error(nvae)
  File "C:\SW_SVN\ScriptConverter\PgenToAntlr\antlr\ITPParser.py", line 124155, 
in error
    self._dbg.recognitionException(nvae)
AttributeError: 'DFA22' object has no attribute '_dbg'>

I noted that _dbg is an attribute of some classes in debug.py in antlr3 folder 
but not of DFA class (of which DFA22 is subclass).  So I am assuming this is a 
incomplete coding or a bug?  Is there any quick fix workaround that can be 
recommended?

Thanks in advance for any guidance.
Mark

PS Java is not an option here due to having a large grammar and hitting the 
Java 64K module limit.