tramp (2.0.50); reset coding-system after save-buffer

[SUGITA Toshinori]

Enter your bug report in this message, including as much detail as you
possibly can about the problem, what you did to cause it and what the
local and remote machines are.

If you can give a simple set of instructions to make this bug happen
reliably, please include those.  Thank you for helping kill bugs in
TRAMP.

Another useful thing to do is to put (setq tramp-debug-buffer t) in
the ~/.emacs file and to repeat the bug.  Then, include the contents
of the *tramp/foo* buffer and the *debug tramp/foo* buffer in your bug
report.

--bug report follows this line--

My Emacs got strange action.

1. set ssh's process-coding-system set to 'undecided'.
   (modify-coding-system-alist 'process "ssh" '(undecided . unix))

2. open a new file /scp:some-server:/some-where/new-file
   -> '-' coding system sign is indicated in mode line.
   and write Japanese charactors into buffer.
   or a existing file included japanese charactors.

3. M-x set-buffer-file-coding-system -> euc-jp
   -> 'E' coding system sign is indicated in mode line.

4. M-x save-buffer
   -> '-' coding system sign is indicated again!
   file saved in EUC-JP encoding.

5. M-x save-buffer again.
   file saved in utf-8 encoding by automatic deciding coding-system

if re-read saved file between 4 and 5 then mode line indicates 'E' sign
correctly.

Can I avoid this in some settings?
Or I may wait bug fix?

Sorry, my poor English.
regards.


Emacs  : GNU Emacs 21.4.1 (i386-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2005-03-18 on trouble, modified by Debian
Package: tramp (2.0.50)