PL/Python function with psycopg2 cannot connect to remote postgres

For one use case I want to connect to external postgreSQL database from HAWQ PL/Python procedure.
I use python psycopg2 library.
Remote postgreSQL server reject connecion from HAWQ with
this error : FATAL unsupported frontend protocol 28675.0: server supports 1.0 to 3.0.
The same python code is running well from OS level.

I wonder if it is HAWQ or PostgreSQL PL/Python interpreter related issiue.
Any help or pointers would be great.

-----------------------
my code below:

CREATE OR REPLACE FUNCTION dchoma.connection_test( ) RETURNS text AS
$$
import psycopg2

try:
conn = psycopg2.connect("dbname='database_name' user='user' host='remote_host' password='pass' port=5432")
return "Connection successful "
except Exception , msg :
return "Exception:

".format(m=msg)
$$
LANGUAGE 'plpythonu' VOLATILE;

select * from dchoma.connection_test();

HAWQ version 2.0.1.0 build dev ( compiled from github)
Remote database version: PostgreSQL 9.2.15 on x86_64-redhat-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-4), 64-bit
OS: CentOS 7-1511

i found similar issiue here, but the problem is not solved.
https://discuss.zendesk.com/hc/en-us/community/posts/200793368-greenplum-dblink-postgresql-remote-is-error