BUG #4525: substring with this pattern works in 8.3.1; does not work in 8.3.4

The following bug has been logged online:

Bug reference:      4525
Logged by:          chris wood
Email address:      chrisj.wood@sympatico.ca
PostgreSQL version: 8.3.4
Operating system:   Debian
Description:        substring with this pattern works in 8.3.1; does not
work in 8.3.4
Details:

I apologize in advance for not testing  on 8.3.5,  but that would be very
difficult for me.

I e-mailed this same problem from chris.wood@bookitnow.ca and it got
blocked

here is where it works in 8.3.1:
protocalte=> select version() ;
                                        version
----------------------------------------------------------------------------
------------
 PostgreSQL 8.3.1 on i486-pc-linux-gnu, compiled by GCC cc (GCC) 4.2.3
(Debian 4.2.3-2)
(1 row)

protocalte=> CREATE TABLE locn (
    locn_key integer NOT NULL,
    public_phone text NOT NULL,
    CONSTRAINT public_phone_ch CHECK (((public_phone = ''::text) OR
("substring"(public_phone, '^[0-9]{10}(,[0-9]{10})*$'::text) IS NOT NULL)))
);
CREATE TABLE
protocalte=> insert into locn values(10, '1231231234') ;
INSERT 0 1

and here is where it does not work in 8.3.4:
postgresbugs=# select version() ;
                                          version
----------------------------------------------------------------------------
----------------
 PostgreSQL 8.3.4 on i486-pc-linux-gnu, compiled by GCC gcc-4.3.real (Debian
4.3.2-1) 4.3.2
(1 row)

postgresbugs=# CREATE TABLE locn (
    locn_key integer NOT NULL,
    public_phone text NOT NULL,
    CONSTRAINT public_phone_ch CHECK (((public_phone = ''::text) OR
("substring"(public_phone, '^[0-9]{10}(,[0-9]{10})*$'::text) IS NOT NULL)))
);
CREATE TABLE
postgresbugs=# insert into locn values(10, '1231231234') ;
ERROR:  new row for relation "locn" violates check constraint
"public_phone_ch"