>>> 
>>> >> ~/web/emacs $ which grep
...
>>> >> emacs_n_unicode.html                        xah_emacs_linkify.el~
>>> >> ~/web/emacs $
...
>>> >
>>> >
>>> > Why do you think predictable behaviour is nice? ;-)
>>> >
>>> > Ok, you discovered the bug so it is your turn to file a bug report again ...
>>> 
>>> don't think its a bug. This is eshell not handling redirection correclty
>>> and is something that cannot be easily fixed. Bottom line, don't use
>>> redirection in eshell.
>>
>> FWIW, I don't see anything wrong with the above: just unwrap the
>> obviously wrapped lines, and you will see that everything is
>> honky-dory.
>
> But it's different from how bash + ls behave in a "normal" terminal.
> When stdout for the `ls' command is not a tty it prints one file per
> line (IMHO the right way).
>
> David

Well, I just dug out coreutils' sources. In ls.c, line 1423 in the
function decode_switches, the magic reveals itself: