I'm installing devstack on my RHEL 7 VM. While installing the nova, its throwing the following error. How can i resolve this. Should i need to change the code in all the trace back files or any package is available which can resolve this issue? (The python version is 2.7)

 Traceback (most recent call last):
 File "/usr/bin/nova-manage", line 10, in <module>
 sys.exit(main())
 File "/opt/stack/nova/nova/cmd/manage.py", line 1725, in main
 config.parse_args(sys.argv)
File "/opt/stack/nova/nova/config.py", line 55, in parse_args
rpc.init(CONF)
File "/opt/stack/nova/nova/rpc.py", line 63, in init
TRANSPORT = create_transport(get_transport_url())
File "/opt/stack/nova/nova/rpc.py", line 172, in get_transport_url
return messaging.TransportURL.parse(CONF, url_str)
File "/usr/lib/python2.7/site-packages/debtcollector/removals.py", line 261, in wrapper
return f(*args, **kwargs)
File "/usr/lib/python2.7/site-packages/oslo_messaging/transport.py", line 558, in parse
port = int(port)
ValueError: invalid literal for int() with base 10: 'abc'