PL/pgSQL RAISE EXCEPTION ignores escape characters even with new E'' string syntax

PostgreSQL 8.1.9

According to the release notes, PostgreSQL still handles escape characters in strings as it has in the past, yet PL/pgSQL functions that use escape characters within the string definition for RAISE EXCEPTION are ignored, unless the function is created using the old style quote definition (not $$).

Observe the following four test functions using PL/pgSQL.

CREATE OR REPLACE FUNCTION test_func_exception() RETURNS void AS '
BEGIN
RAISE EXCEPTION \'This is an error message.\nThis is a message on a new line\';
RETURN;
END '
LANGUAGE 'plpgsql' VOLATILE SECURITY DEFINER;

CREATE OR REPLACE FUNCTION test_func_exception2() RETURNS void AS
$BODY$
BEGIN
RAISE EXCEPTION 'This is an error message.\nThis is a message on a new line';
RETURN;
END $BODY$
LANGUAGE 'plpgsql' VOLATILE SECURITY DEFINER;

CREATE OR REPLACE FUNCTION test_func_exception3() RETURNS void AS
$BODY$
BEGIN
RAISE EXCEPTION E'This is an error message.\nThis is a message on a new line';
RETURN;
END $BODY$
LANGUAGE 'plpgsql' VOLATILE SECURITY DEFINER;

CREATE OR REPLACE FUNCTION test_func_exception4() RETURNS void AS
$BODY$
DECLARE
smessage text;
BEGIN
smessage := 'This is an error message.\nThis is a message on a new line';
RAISE EXCEPTION '%',smessage;
RETURN;
END $BODY$
LANGUAGE 'plpgsql' VOLATILE SECURITY DEFINER;

Out put from the four test functions are as follows:

1)
select test_func_exception();
ERROR: This is an error message.
This is a message on a new line

2)
select test_func_exception2();
ERROR: This is an error message.nThis is a message on a new line

3)
select test_func_exception3();
ERROR: This is an error message.nThis is a message on a new line

4)
select test_func_exception4();
ERROR: This is an error message.
This is a message on a new line

You will note that even using the new E'' string format syntax for the RAISE EXCEPTION appears to be broken (test_func_exception3()).
I can't find anything in the documentation that suggests this should be the observed behaviour.

Regards
Donald Fraser