Cloned from https://bugzilla.redhat.com/show_bug.cgi?id=1113014
Description of problem:
I was trying to create a new host via UI and filled the form with all necessary info. But when I submit the form the firebug raised following error:

"NetworkError: 500 Internal Server Error - https://dhcp207-190.lab.eng.pnq.redhat.com/hosts/shost.katellolabs.org/vm"
vm
ReferenceError: _ is not defined

snippet from production.log ============================
Processing by HostsController#vm as HTML
Parameters: {"id"=>"shost.katellolabs.org"}
Operation FAILED: can't convert nil into String
Rendered common/500.html.erb (10.2ms)
Completed 500 Internal Server Error in 46ms (Views: 15.4ms | ActiveRecord: 3.8ms)

Version-Release number of selected component (if applicable):
sat6 beta snap10 compose3

How reproducible:
tried once

Steps to Reproduce:
1. created new hostgroup and selected activation-key
2. filled up "New Host" form first with hostgroup and then unselect it
3. Filled all other details and submit the form

Actual results:
Processing by HostsController#vm as HTML
Parameters: {"id"=>"shost.katellolabs.org"}
Operation FAILED: can't convert nil into String
Rendered common/500.html.erb (10.2ms)
Completed 500 Internal Server Error in 46ms (Views: 15.4ms | ActiveRecord: 3.8ms)

Expected results:
host should be created successfully

Additional info: