Description of problem:
Run a cluster install behind proxy, and set openshift_portal_net in inventory host file, "Set fact of no_proxy_internal_hostnames" task failed.
 
Version-Release number of the following components:
openshift-ansible-3.9.0-0.36.0.git.0.da68f13.el7.noarch

How reproducible:
Always

Steps to Reproduce:
1. Setting the following options in inventory file.
openshift_http_proxy=http://file.rdu.redhat.com:3128
openshift_https_proxy=http://file.rdu.redhat.com:3128
openshift_no_proxy="169.254.169.254,.lab.sjc.redhat.com"
openshift_portal_net=172.31.0.0/16
2. Trigger a cluster install without direct internet access.
3.

Actual results:
TASK [Set fact of no_proxy_internal_hostnames] *********************************
Saturday 03 February 2018  10:53:51 +0000 (0:00:08.839)       0:00:23.866 ***** 

An exception occurred during task execution. To see the full traceback, use -vvv. The error was: TypeError: decoding Unicode is not supported
fatal: [aos-129.lab.sjc.redhat.com]: FAILED! => {"changed": false, "module_stderr": "Traceback (most recent call last):\n  File \"/tmp/ansible_J8xt_Z/ansible_module_openshift_facts.py\", line 1687, in <module>\n    main()\n  File \"/tmp/ansible_J8xt_Z/ansible_module_openshift_facts.py\", line 1674, in main\n    additive_facts_to_overwrite)\n  File \"/tmp/ansible_J8xt_Z/ansible_module_openshift_facts.py\", line 1339, in __init__\n    additive_facts_to_overwrite)\n  File \"/tmp/ansible_J8xt_Z/ansible_module_openshift_facts.py\", line 1384, in generate_facts\n    facts = set_proxy_facts(facts)\n  File \"/tmp/ansible_J8xt_Z/ansible_module_openshift_facts.py\", line 1151, in set_proxy_facts\n    kube_svc_ip = str(ipaddress.ip_network(u(common['portal_net']))[1])\n  File \"/tmp/ansible_J8xt_Z/ansible_modlib.zip/ansible/module_utils/six/__init__.py\", line 650, in u\nTypeError: decoding Unicode is not supported\n", "module_stdout": "", "msg": "MODULE FAILURE", "rc": 1}

An exception occurred during task execution. To see the full traceback, use -vvv. The error was: TypeError: decoding Unicode is not supported
fatal: [aos-136.lab.sjc.redhat.com]: FAILED! => {"changed": false, "module_stderr": "Traceback (most recent call last):\n  File \"/tmp/ansible_JVs7hJ/ansible_module_openshift_facts.py\", line 1687, in <module>\n    main()\n  File \"/tmp/ansible_JVs7hJ/ansible_module_openshift_facts.py\", line 1674, in main\n    additive_facts_to_overwrite)\n  File \"/tmp/ansible_JVs7hJ/ansible_module_openshift_facts.py\", line 1339, in __init__\n    additive_facts_to_overwrite)\n  File \"/tmp/ansible_JVs7hJ/ansible_module_openshift_facts.py\", line 1384, in generate_facts\n    facts = set_proxy_facts(facts)\n  File \"/tmp/ansible_JVs7hJ/ansible_module_openshift_facts.py\", line 1151, in set_proxy_facts\n    kube_svc_ip = str(ipaddress.ip_network(u(common['portal_net']))[1])\n  File \"/tmp/ansible_JVs7hJ/ansible_modlib.zip/ansible/module_utils/six/__init__.py\", line 650, in u\nTypeError: decoding Unicode is not supported\n", "module_stdout": "", "msg": "MODULE FAILURE", "rc": 1}

Expected results:
installation is completed successfully.

Additional info:
Seem like this is introduced by https://github.com/openshift/openshift-ansible/pull/6215