BUG #13811: Default ordering colums

The following bug has been logged on the website:

Bug reference: 13811
Logged by: Vyacheslav
Email address: exru(at)mail(dot)ru
PostgreSQL version: 9.4.5
Operating system: Debian 8.1
Description:

--1) create table and make batch insert of values

CREATE TABLE auction
(
id serial NOT NULL primary key,
name text,
type smallint,
client_id integer,
description text,
category_id integer,
dt_start timestamp(0) without time zone,
dt_end timestamp(0) without time zone,
status smallint DEFAULT 1
);

INSERT INTO "auction" ("id", "name", "type", "client_id", "description",
"status", "category_id", "dt_start", "dt_end") VALUES (0, 'Аукцион1', 1, 1,
'Аукцион0', -1, 5, '2015-12-10 15:38:00', NULL), (1, 'Аукцион1', -1, 1,
'Аукцион1', 0, 5, '2015-12-10 15:38:00', NULL), (2, 'Аукцион2', 1, 1,
'Аукцион2', 1, 5, '2015-12-10 15:38:00', NULL), (3, 'Аукцион3', 1, 1,
'Аукцион3', 1, 5, '2015-12-10 15:38:00', NULL), (4, 'Аукцион4', 1, 1,
'Аукцион4', 3, 7, '2015-12-10 15:38:00', NULL), (5, 'Аукцион5', 1, 1,
'Аукцион5', 4, 5, '2015-12-10 15:38:00', NULL), (6, 'Аукцион6', 1, 1,
'Аукцион6', 5, 6, '2015-12-10 15:38:00', NULL), (7, 'Аукцион7', -1, 1,
'Аукцион7', 6, 6, '2015-12-10 15:38:00', NULL), (8, 'Аукцион7', 1, 1,
'Аукцион7', 7, 7, '2015-12-10 15:38:00', NULL);

2) then i maked a select (SELECT * FROM auction;) i've get the next rows
with orders:

0;"Аукцион1";1;1;"Аукцион0";5;"2015-12-10 15:38:00";"";-1
1;"Аукцион1";-1;1;"Аукцион1";5;"2015-12-10 15:38:00";"";0
2;"Аукцион2";1;1;"Аукцион2";5;"2015-12-10 15:38:00";"";1
3;"Аукцион3";1;1;"Аукцион3";5;"2015-12-10 15:38:00";"";1
4;"Аукцион4";1;1;"Аукцион4";7;"2015-12-10 15:38:00";"";3
5;"Аукцион5";1;1;"Аукцион5";5;"2015-12-10 15:38:00";"";4
6;"Аукцион6";1;1;"Аукцион6";6;"2015-12-10 15:38:00";"";5
7;"Аукцион7";-1;1;"Аукцион7";6;"2015-12-10 15:38:00";"";6
8;"Аукцион7";1;1;"Аукцион7";7;"2015-12-10 15:38:00";"";7

3) the make the:
UPDATE "auction" SET "type"=1, "client_id"=1, "dt_start"='2015-12-10
15:38:00', "status"=-1 WHERE "id"=0; //data in the raw was not changed bat
the (SELECT * FROM auction;) give me the next order of rows:

1;"Аукцион1";-1;1;"Аукцион1";5;"2015-12-10 15:38:00";"";0
2;"Аукцион2";1;1;"Аукцион2";5;"2015-12-10 15:38:00";"";1
3;"Аукцион3";1;1;"Аукцион3";5;"2015-12-10 15:38:00";"";1
4;"Аукцион4";1;1;"Аукцион4";7;"2015-12-10 15:38:00";"";3
5;"Аукцион5";1;1;"Аукцион5";5;"2015-12-10 15:38:00";"";4
6;"Аукцион6";1;1;"Аукцион6";6;"2015-12-10 15:38:00";"";5
7;"Аукцион7";-1;1;"Аукцион7";6;"2015-12-10 15:38:00";"";6
8;"Аукцион7";1;1;"Аукцион7";7;"2015-12-10 15:38:00";"";7
0;"Аукцион1";1;1;"Аукцион0";5;"2015-12-10 15:38:00";"";-1

4) There is no any orders by or any changes in sequences. Why do that???