The `strsignal(SIGNUM)' function from libc returns a pointer to a string
containing a message describing the signal SIGNUM.

Emacs `status_message' function from `src/process.c' attempts to
downcase the initial character of this string to print it in the echo
area:

    signame = strsignal (code);
    string = build_string (signame);
    SSET (string, 0, DOWNCASE (SREF (string, 0)));

As it has already been discussed in bug #778, using SSET/SREF is
incorrect when `string' is multibyte, which is the case for certain
locales like ru_RU.UTF-8. A patch similar to one proposed by Kenichi
Handa for bug #778 fixes this problem, too. The patch is attached.