Mats Löfdahl <mats_lofdahl@yahoo.se> writes:

> I then started a fresh emacs and did the double attempt to connect as
> root. To me it looked just like last time but I've uploaded the debug
> buffer anyway: http://www.solarphysics.kva.se/~mats/debug3.txt

Things progress. Still an error, but at another place.

Tramp has two problems with your Busybox: it echoes the commands, and it
is slow. This case, when Tramp has send "PS1='$ '", only the "PS1='$"
substring was visible in the output buffer, and Tramp thought it is a
shell prompt. Then it has sent the next command, and it began to be
confused by the not read characters.

So we must convince Tramp there isn't a shell prompt, even if the
command itself is echoed, and even if only a substring of the whole
command is visible.

The appended patch tries to catch this situation. Could you, please,
test?

Thanks, and best regards, Michael.