> aaugustin <aymeric.augustin@polyconseil.fr> added the comment:
> 
> I agree with your solution. Unfortunately, I do not know how you would
> redefine ThreadError to extend RuntimeError in a C extension.
> 
> _thread.error is created line 741 in trunk/Modules/threadmodule.c:
> ThreadError = PyErr_NewException("thread.error", NULL, NULL);

I was not proposing to extend it, just to alias it:

ThreadError = PyExc_RuntimeError;
Py_INCREF(ThreadError);

That said, extending is quite trivial if the behaviour is not changed:

ThreadError = PyErr_NewException("thread.error", PyExc_RuntimeError,
NULL);

(see
http://docs.python.org/dev/c-api/exceptions.html#PyErr_NewException)