Description of problem:
Faield to ugprade to v3.6 using atomic-openshift-installer.  There is a similar bug in v3.5 https://bugzilla.redhat.com/show_bug.cgi?id=1421033

Version-Release number of selected component (if applicable):
atomic-openshift-utils-3.6.42-1.git.0.2b420c1.el7.noarch

How reproducible:
always

Steps to Reproduce:
1. install OCP 3.5
2. atomic-openshift-installer

Actual results:
1. install OCP 3.5
2. atomic-openshift-installer upgrade


Expected results:
[root@upg-jenkins-slave-preserve ~]# atomic-openshift-installer upgrade

        This tool will help you upgrade your existing OpenShift installation.
        Currently running: openshift-enterprise 3.5

(1) Update to latest 3.5
(2) Upgrade to next release: 3.6

Choose an option from above: 2
OpenShift will be upgraded from openshift-enterprise 3.5 to latest openshift-enterprise 3.6 on the following hosts:

  * openshift-142.lab.sjc.redhat.com
  * openshift-103.lab.sjc.redhat.com
  * openshift-135.lab.sjc.redhat.com
  * openshift-148.lab.sjc.redhat.com
  * openshift-148.lab.sjc.redhat.com

Do you want to proceed? [y/N]: y
Traceback (most recent call last):
  File "/usr/bin/atomic-openshift-installer", line 9, in <module>
    load_entry_point('ooinstall==3.0.0', 'console_scripts', 'oo-install')()
  File "/usr/lib/python2.7/site-packages/click/core.py", line 664, in __call__
    return self.main(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/click/core.py", line 644, in main
    rv = self.invoke(ctx)
  File "/usr/lib/python2.7/site-packages/click/core.py", line 991, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/lib/python2.7/site-packages/click/core.py", line 837, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/lib/python2.7/site-packages/click/core.py", line 464, in invoke
    return callback(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/ooinstall/cli_installer.py", line 1025, in upgrade
    ctx.obj['verbose'])
  File "/usr/lib/python2.7/site-packages/ooinstall/openshift_ansible.py", line 331, in run_upgrade_playbook
    inventory_file = generate_inventory(hosts)
  File "/usr/lib/python2.7/site-packages/ooinstall/openshift_ansible.py", line 63, in generate_inventory
    write_inventory_vars(base_inventory, lb)
  File "/usr/lib/python2.7/site-packages/ooinstall/openshift_ansible.py", line 140, in write_inventory_vars
    base_inventory.write('deployment_type={}\n'.format(ver.ansible_key))
AttributeError: 'NoneType' object has no attribute 'ansible_key'



Additional info: