BUG #7499: wrong data sorting if I use "...limit 1..." SQL clause along with "...order by ..."

The following bug has been logged on the website:

Bug reference: 7499
Logged by: Denis Kolesnik
Email address: lirex.software@gmail.com
PostgreSQL version: 9.1.3
Operating system: Windows XP Home Edition Service Pack 3 OEM
Description:

firstly a schema of my table:

-- Name: tbl_owners_individual; Type: TABLE; Schema: public; Owner: lurtz;
Tablespace:
--

CREATE TABLE tbl_owners_individual (
id integer NOT NULL,
str_first_name character(20),
str_last_name character(20),
dt_birth date,
str_email character(40),
str_sex character(1),
int_icq bigint,
str_nickname character(30),
str_cellphone character(14),
str_comment character(50)
);

ALTER TABLE public.tbl_owners_individual OWNER TO lurtz;

SET default_with_oids = false;

--
-- Name: tbl_owners_individual_id_seq; Type: SEQUENCE; Schema: public;
Owner: lurtz
--

CREATE SEQUENCE tbl_owners_individual_id_seq
INCREMENT BY 1
NO MAXVALUE
NO MINVALUE
CACHE 1;

ALTER TABLE public.tbl_owners_individual_id_seq OWNER TO lurtz;

--
-- Name: tbl_owners_individual_id_seq; Type: SEQUENCE OWNED BY; Schema:
public; Owner: lurtz
--

ALTER SEQUENCE tbl_owners_individual_id_seq OWNED BY
tbl_owners_individual.id;

--
-- Name: tbl_owners_individual_id_seq; Type: SEQUENCE SET; Schema: public;
Owner: lurtz
--

SELECT pg_catalog.setval('tbl_owners_individual_id_seq', 51, true);

ALTER TABLE tbl_owners_individual ALTER COLUMN id SET DEFAULT
nextval('tbl_owners_individual_id_seq'::regclass);

----

the problem:

there are 4 queries:
1. select id, str_last_name from tbl_owners_individual order by
str_last_name;

...
49 | Kolesnik
224 | Kolesnik
144 | Kolesnik
1 | Kolesnik
...

2. select id, ' ', regexp_replace(str_last_name,' ','') as lastname, ' ',
regexp_replace(str_first_name,' ','') as firstname, ' ', age(dt_birth) as
age from tbl_owners_individual order by str_last_name;

...
49 | | Kolesnik | | XXXXX | | XX
years X mons XX days
224 | | Kolesnik | | XXXXXX | | X
years XX mons XX days
144 | | Kolesnik | | XXXXXXXXXX | | XX
years XX mons XX days
1 | | Kolesnik | | Denis | | 31
years 4 mons 21 days
...

(I replaced with X sensitive information)

3. select id, str_last_name from tbl_owners_individual order by
str_last_name offset 53;

...
1 | Kolesnik
111 | Kolesnik
251 | XXXXXXXXXX
112 | XXXXX
...

4. select id, str_last_name from tbl_owners_individual order by
str_last_name limit 1 offset 53;

111 | Kolesnik

the 4-rd query should return

1 | Kolesnik
instead of
111 | Kolesnik

Regards,
Denis Kolesnik.