Bus Error in psql command history

I run psql on Mac OS X:

psql (8.4.1, server 8.4.0)

Then paste the following in, having been copied from an XCode editor
window:

CREATE OR REPLACE FUNCTION compute_mw_realname (
     nicknames text,
     givennames text,
     surname text
) RETURNS text AS $$
     DECLARE
         first text;
         last text;
     BEGIN
         last := replace (trim (surname), '-', '');
         IF nicknames IS NOT NULL THEN
             first := replace (trim (nicknames), '-', '');
             IF substring (first from 1 + length (first) - length (last))
              = last THEN
                 first := trim (substring
                  (first from 1 for length (first) - length (last)));
                 IF first = '' THEN
                     first = replace (trim (givennames), '-', '');
                 END IF;
             END IF;
         ELSE
             first := replace (trim (givennames), '-', '');
         END IF;
         first = replace (first, '-', '');
         RETURN upper (substring (first from 1 for 1)) ||
          substring (first from 2) || ' ' || last;
     END;
$$ LANGUAGE PLPGSQL IMMUTABLE;

After this executes, which it does successfully, if I use cursor-up to
re-display this command, I get an immediate bus error and psql quits.

If I don't use cursor-up, I can continue typing commands, but if I later
cursor-up far enough that the above command should be re-displayed then I
get the bus error at that time.

Works fine on psql 8.4.1 for Solaris.

Please advise if you would like any more details about the behaviour.  I
can think of a few things to investigate but none that jumps out as the
obvious thing to look into.

Isaac Morland            CSCF Web Guru
DC 2554C, x36650        WWW Software Specialist