Download my branch of sympy from here:

http://github.com/certik/sympy/tree/division3

and run the 2to3 tool with python2.5:

$ python2.5 ../2to3/2to3 sympy/
[...]
Traceback (most recent call last):
  File "../2to3/2to3", line 6, in <module>
    sys.exit(main("lib2to3.fixes"))
  File "/home/ondra/repos/2to3/lib2to3/main.py", line 126, in main
    rt.refactor(args, options.write, options.doctests_only)
  File "/home/ondra/repos/2to3/lib2to3/refactor.py", line 194, in refactor
    self.refactor_dir(dir_or_file, write, doctests_only)
  File "/home/ondra/repos/2to3/lib2to3/refactor.py", line 212, in
refactor_dir
    self.refactor_file(fullname, write, doctests_only)
  File "/home/ondra/repos/2to3/lib2to3/refactor.py", line 235, in
refactor_file
    tree = self.refactor_string(input, filename)
  File "/home/ondra/repos/2to3/lib2to3/refactor.py", line 260, in
refactor_string
    self.refactor_tree(tree, name)
  File "/home/ondra/repos/2to3/lib2to3/refactor.py", line 299, in
refactor_tree
    self.traverse_by(self.post_order, tree.post_order())
  File "/home/ondra/repos/2to3/lib2to3/refactor.py", line 323, in
traverse_by
    new = fixer.transform(node, results)
  File "/home/ondra/repos/2to3/lib2to3/fixes/fix_metaclass.py", line
148, in transform
    if not has_metaclass(node):
  File "/home/ondra/repos/2to3/lib2to3/fixes/fix_metaclass.py", line 34,
in has_metaclass
    return has_metaclass(node)
  File "/home/ondra/repos/2to3/lib2to3/fixes/fix_metaclass.py", line 39,
in has_metaclass
    if leaf_node.value == '__metaclass__':
AttributeError: 'Node' object has no attribute 'value'

I've fixed the first problem in r67177, but I found another one in
thirdparty/pyglet. Try running with "-x metaclass".

Thanks, that was quick!

You can delete the thirdparty/pyglet, it's not imported by default. Then
the 2to3 passes. But I found another bug:

issue 4292

You would like to replace "from mptypes import ..." by "from .mptypes 
import ...". Is it really a bug? Python is unable to guess if mptypes, 
functions or settings are "global" modules or "relative" modules. Why 
don't you patch your original code since Python 2.5 also supports this 
syntax? Documentation:
http://www.python.org/doc/2.5.2/ref/import.html
http://docs.python.org/reference/simple_stmts.html#the-import-statement

Hi Victor, thanks for the comments. I copied them to the issue 4292
where they belong and replied there.

Second metaclass problem fixed in r67178.

I can confirm this is now fixed. Thanks very much!