Description of problem:
Upgrade ocp3.4 to ocp3.5 with quick installer tool, after confirm for the printed host info, quick upgrade can not proceed to run upgrade playbook due to variant version wrong.

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 1039, 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'


Version-Release number of selected component (if applicable):
atomic-openshift-utils-3.5.6-1.git.0.5e6099d.el7.noarch

How reproducible:
always

Steps to Reproduce:
1.Prepare installer.cfy.yml for existed ocp3.4 env.
2.Trigger upgrade with quick installer tool
# atomic-openshift-installer -c /tmp/installer.cfg.yml upgrade
3.

Actual results:
Can not proceed to run upgrade playbook.

Expected results:
Upgrade seccessfully with quick installer tool.

Additional info: