Python2.2 + mailbox. Bug????

[hector]

Hi

  This is my program:

#!/usr/bin/python
import sys
from mailbox import PortableUnixMailbox
tmp = sys.stdin
mbox = PortableUnixMailbox(tmp)
mbox.next()
...
...

  When I execute: "./program.py < mboxfile.txt", there's no problem

  But, if I execute: "cat mboxfile.txt | program.py" ... too bad!

  the error:

Traceback (most recent call last):
  File "./prueba.py", line 8, in ?
    mbox.next()
  File "/usr/lib/python2.2/mailbox.py", line 23, in next
    self.fp.seek(self.seekp)
IOError: [Errno 29] Illegal seek

Why????? Thanks ALL!!