ediff and coding systems

[Dan Nicolaescu <dann@ics.uci.edu>]

lisp/term/mac-win.el from CVS trunk uses:  -*-coding: iso-2022-7bit;-*-
and the same file on the emacs-unicode-2 uses: -*-coding: utf-8 

When doing M-x ediff for the above 2 files a *Warning* buffer pops up
for each hunk:

These default coding systems were tried to encode text
in the buffer ` *ediff-tmp*':
  iso-latin-1
However, each of them encountered characters it couldn't encode:
  iso-latin-1 cannot encode these: ? ? ? ? ? ? ? ? ? ? ...

Click on a character (or switch to this window by `C-x o'
and select the characters by RET) to jump to the place it appears,
where `C-u C-x =' will give information about it.

Select one of the safe coding systems listed below,
or cancel the writing with C-g and edit the buffer
   to remove or modify the problematic characters,
or specify any other coding system (and risk losing
   the problematic characters).

  utf-8 utf-16 utf-16 utf-16 utf-16be utf-16le iso-2022-7bit

with the question "Select coding system (default mule-utf-8):"

Would it be possible for ediff to avoid this?