BUG #13699: float type bug

The following bug has been logged on the website:

Bug reference:      13699
Logged by:          digoal
Email address:      digoal@126.com
PostgreSQL version: 9.4.5
Operating system:   CentOS 6.x x64
Description:

postgres=# create table t3(c1 float, c2 numeric);
CREATE TABLE
postgres=# \d t3
           Table "public.t3"
 Column |       Type       | Modifiers
--------+------------------+-----------
 c1     | double precision |
 c2     | numeric          |

postgres=# insert into t3 values (1.55555555555555555555555555555555555,
1.55555555555555555555555555555555555);
INSERT 0 1
postgres=# select * from t3;
        c1        |                  c2
------------------+---------------------------------------
 1.55555555555556 | 1.55555555555555555555555555555555555
(1 row)

but:
postgres=# select * from t3 where c1>=1.55555555555556;
 c1 | c2
----+----
(0 rows)

when we use logical decoding there will replace the real value with
1.55555555555556.

postgres=# SELECT * FROM
pg_create_logical_replication_slot('regression_slot', 'test_decoding');
    slot_name    | xlog_position
-----------------+---------------
 regression_slot | 0/4C4A260
(1 row)

postgres=# SELECT * FROM pg_logical_slot_get_changes('regression_slot',
NULL, NULL);
 location | xid | data
----------+-----+------
(0 rows)

postgres=# create table test(c1 float);
CREATE TABLE
postgres=# SELECT * FROM pg_logical_slot_get_changes('regression_slot',
NULL, NULL);
 location  | xid  |    data
-----------+------+-------------
 0/4C4A2F0 | 9723 | BEGIN 9723
 0/4C5A6D0 | 9723 | COMMIT 9723
(2 rows)

postgres=# insert into test values (1.5555555555555555555555);
INSERT 0 1
postgres=# SELECT * FROM pg_logical_slot_get_changes('regression_slot',
NULL, NULL);
 location  | xid  |                               data

-----------+------+------------------------------------------------------------------
 0/4C5A6D0 | 9724 | BEGIN 9724
 0/4C5A6D0 | 9724 | table public.test: INSERT: c1[double
precision]:1.55555555555556
 0/4C5A758 | 9724 | COMMIT 9724
(3 rows)

and pg_dump use this code resolve the problem.
        if (AH->remoteVersion >= 90000)
                ExecuteSqlStatement(AH, "SET extra_float_digits TO 3");
        else if (AH->remoteVersion >= 70400)
                ExecuteSqlStatement(AH, "SET extra_float_digits TO 2");

in logical decoding , when we use cstring as the output , what we can do?
or we must use bytea output?