rhn-migrate-classic-to-rhsm failing with SyntaxError: invalid syntax

Issue

rhn-migrate-classic-to-rhsm failing with below traceback:

[root@vrhserver ~]# rhn-migrate-classic-to-rhsm
Traceback (most recent call last):
   File "/usr/sbin/rhn-migrate-classic-to-rhsm", line 54, in ?
     from subscription_manager.migrate import migrate
   File "/usr/share/rhsm/subscription_manager/migrate/migrate.py", 
line 34, in ?
     from rhsm.connection import UEPConnection, 
RemoteServerException, RestlibException
   File "/usr/lib/python2.4/site-packages/rhsm/connection.py", line 32, in ?
     from version import Versions
   File "/usr/lib/python2.4/site-packages/rhsm/version.py", line 13, in ?
     from rhsm.profile import RPMProfile
   File "/usr/lib/python2.4/site-packages/rhsm/profile.py", line 17, in ?
     from rhsm import ourjson as json
   File "/usr/lib/python2.4/site-packages/rhsm/ourjson.py", line 22, in ?
     from simplejson import *
   File 
"/usr/lib/python2.4/site-packages/simplejson-2.6.1-py2.4.egg/simplejson/__init__.py", 
line 112, in ?
     from encoder import JSONEncoder
   File 
"/usr/lib/python2.4/site-packages/simplejson-2.6.1-py2.4.egg/simplejson/encoder.py", 
line 400
     if (not _bigint_as_string or
      ^
SyntaxError: invalid syntax