bug#27361: 24.4; eshell/echo silently ignores -n argument

[npostavs]

Phil Hagelberg <phil@hagelb.org> writes:

> When using eshell, the `echo' built-in doesn't respect the -n argument,
> which is supposed to suppress the trailing newline.
>
> Sometimes this is not a problem because you can see for yourself that
> eshell did the wrong thing, but if you are piping it directly to another
> command, it's easy to miss.
>
> The eshell/echo function should be changed to either accept the -n
> argument and omit the newline, or it should complain that -n is not a
> supported argument.

It's not ignored, but eshell always adds a newline before the prompt.
Furthermore, the argument has the opposite sense to the traditional
shell interpretation:

    ~/src $ echo x | od -c
    0000000   x
    0000001
    ~/src $ echo -n x | od -c
    0000000   x  \n
    0000002