bug#17423: bug with 'tee' command

[Pawel Jagla]

Hello

I discovered a bug with 'tee' command when I sort items in file, and try to
overwrite output to the same file, like that :
sort filename |tee filename

Sometimes it sorts and overwrites file with sorted items, and sometimes it
clears the file completely (so the file is empty).
Of course I know that I can do that by adding operator '-o' to sort.
BTW I am working under RedHat 6 Enterprise, and bash shell.

Kind Regards
Pawel Jagla