Table DDL scripts generated by pgAdmin incorrectly show the constraint name using the implicit index name (on Greenplum).

I use pgAdmin III 1.20.0 on a Greenplum database 4.2.6.3, which is based
on PostgreSQL 8.2.15.
I'm aware that this version of PostgreSQL is no more supported by pgAdmin.

I noticed that the DDL scripts generated by pgAdmin for the tables,
incorrectly show the constraint name using the implicit index name instead.
I don't know if the same bug exist using pgAdmin with PostgreSQL, but
this could be easily verified.

Steps to reproduce the problem:

1. Create a table with a primary key constraint:

CREATE TABLE public.table_t
(
col_a character varying(50) NOT NULL,
col_b integer NOT NULL,
col_c integer,
CONSTRAINT pk_table_t PRIMARY KEY (col_a, col_b)
)
DISTRIBUTED BY (col_a, col_b);

(DISTRIBUTED BY is a Greenplum option, used to indicate the distribution
key of the table)

2. During the creation of the table, the following message is shown:

NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index
"table_t_pkey" for table "table_t"

Indeed, besides the constraint pk_table_t, an index called table_t_pkey
(<table_name>_pkey) is automatically created.

3. Now let's see the DDL script generated by pgAdmin for this table.
pgAdmin shows the constraint using the implicit index name instead of
the constraint name:

CREATE TABLE public.table_t
(
col_a character varying(50) NOT NULL,
col_b integer NOT NULL,
col_c integer,
CONSTRAINT table_t_pkey PRIMARY KEY (col_a, col_b)
)
WITH (
OIDS=FALSE
)
DISTRIBUTED BY (col_a, col_b);

This issue was present also on pgAdmin 1.16.1 and 1.18.1.

The DDL script generated by Aginity Workbench shows the constraint with
the correct name:

CREATE TABLE public.table_t
(
col_a CHARACTER VARYING(50) NOT NULL,
col_b INTEGER NOT NULL,
col_c INTEGER
)
DISTRIBUTED BY (col_a, col_b);

ALTER TABLE public.table_t
ADD CONSTRAINT pk_table_t
PRIMARY KEY (col_a, col_b);