Problem redirecting stdin on Windows

[aurora]

On Windows (XP) with win32 extension installed, a Python script can be  
launched from the command line directly since the .py extension is  
associated with python. However it fails if the stdin is piped or  
redirected.

Assume there is an echo.py that read from stdin and echo the input.



Launching from command line directly, this echos input from keyboard:

   echo.py



But it causes an error if the stdin is redirected

   echo.py <textfile


   ...
       for line in fp:
   IOError: [Errno 9] Bad file descriptor



However it works as expected if launched via Python.exe

   c:\Python24\python.exe echo.py <textfile



Why is the second option fails? It makes many script lot less functional.