Hello!

There exists a sequence of characters (reproduced below, mistakenly
produced by merely copy pasting accentuated sequences from my browser to
Emacs, even when emacs was started with "emacs -q"), which

 1. generates a warning message on saving ("These default coding systems
    were tried to encode text in the buffer (...)", full message
    included below);
 2. roughly doubles size each time I save it in raw-mode; and
 3. creates such a sequence from any accentuated character (e.g. é) in
    the file (which when copy pasted to other files, "infect" such a
    file and "seeds" other accentuated characters)

As a result, the size of text files can grow quite out of proportions:
the size of the file is getting exponential in the number of times it
was saved, which is obviously undesirable. I will solve the problem by
avoiding raw-mode but thought it could be of interest to you.

Please find more specifics below. Hope it helps!
-- 
Jeremy                             (http://www.dcc.uchile.cl/~jbarbay)

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Specifics:
 
 - An example of "Viral" sequence is "à¥