Calling the following extension function 

static PyObject *
baz(PyObject *self, PyObject *args, PyObject *keywds)
{
  static char *kwlist[] = {NULL};
  if (!PyArg_ParseTupleAndKeywords(args,keywds,"|:bar.baz", kwlist))
    return NULL;
  return Py_BuildValue("");
}

raises

  RuntimeError: more argument specifiers than keyword list entries
(remaining format:'|:bar.baz')

in Python 2.6 but it used to work with earlier versions of Python.

This bug breaks all f2py generated extension modules when using Python 2.6.