Can't save changed page on Windows

Traceback (most recent call last):
  File "c:\Python25\lib\wsgiref\handlers.py", line 92, in run
    self.result = application(self.environ, self.start_response)
  File "c:\Python25\lib\werkzeug\utils.py", line 1539, in <lambda>
    return _patch_wrapper(f, lambda *a: f(*a)(*a[-2:]))
  File "D:\Wayfinder\a\hatta.py", line 1487, in application
    response = endpoint(request, **values)
  File "D:\Wayfinder\a\hatta.py", line 1054, in save
    self.storage.save_text(title, data, author, comment)
  File "D:\Wayfinder\a\hatta.py", line 104, in save_text
    self.save_file(title, file_name, author, comment)
  File "D:\Wayfinder\a\hatta.py", line 90, in save_file
    os.rename(file_name, file_path)
WindowsError: [Error 183] Cannot create a file when that file already exists