That fix is not correct. For instance consider:

>>> code2 = """\
... def foo():
...    x = 42
...    def bar():
...       return -1
... """
>>> top.get_children()[0]
<Function SymbolTable for foo in ?>
>>> top = symtable.symtable(code2, "?", "exec")
>>> top.get_children()[0].lookup('x')._Symbol__scope == symtable.LOCAL
True

but if we return x from bar:

>>> code = """\
... def foo():
...    x = 42
...    def bar():
...       return x
... """
>>> import symtable
>>> top = symtable.symtable(code, "?", "exec")
>>> top.get_children()[0].lookup('x')._Symbol__scope == symtable.LOCAL
False