Description of problem:
-------------------------
The UI blows up with this error while clicking Assigned profile link from a policy event bubble:
No Class found for explorer tree node id 'pp_16' [miq_policy/explorer]

Snippet from production.log:

[----] I, [2015-11-18T17:07:27.097443 #14569:b6f990]  INFO -- :   Parameters: {"profile"=>"16"}
[----] F, [2015-11-18T17:07:27.622049 #14569:b6f990] FATAL -- : Error caught: [RuntimeError] No Class found for explorer tree node id 'pp_16'
/var/www/miq/vmdb/app/controllers/application_controller/explorer.rb:233:in `valid_active_node'
/var/www/miq/vmdb/app/controllers/miq_policy_controller.rb:449:in `get_node_info'
/var/www/miq/vmdb/app/controllers/miq_policy_controller.rb:268:in `explorer'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/action_controller/metal/implicit_render.rb:4:in `send_action'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/abstract_controller/base.rb:198:in `process_action'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/action_controller/metal/rendering.rb:10:in `process_action'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/abstract_controller/callbacks.rb:20:in `block in process_action'
/opt/rh/cfme-gemset/gems/activesupport-4.2.5/lib/active_support/callbacks.rb:117:in `call'
/opt/rh/cfme-gemset/gems/activesupport-4.2.5/lib/active_support/callbacks.rb:117:in `call'
/opt/rh/cfme-gemset/gems/activesupport-4.2.5/lib/active_support/callbacks.rb:555:in `block (2 levels) in compile'
/opt/rh/cfme-gemset/gems/activesupport-4.2.5/lib/active_support/callbacks.rb:505:in `call'
/opt/rh/cfme-gemset/gems/activesupport-4.2.5/lib/active_support/callbacks.rb:505:in `call'
/opt/rh/cfme-gemset/gems/activesupport-4.2.5/lib/active_support/callbacks.rb:92:in `__run_callbacks__'
/opt/rh/cfme-gemset/gems/activesupport-4.2.5/lib/active_support/callbacks.rb:778:in `_run_process_action_callbacks'
/opt/rh/cfme-gemset/gems/activesupport-4.2.5/lib/active_support/callbacks.rb:81:in `run_callbacks'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/abstract_controller/callbacks.rb:19:in `process_action'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/action_controller/metal/rescue.rb:29:in `process_action'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/action_controller/metal/instrumentation.rb:32:in `block in process_action'
/opt/rh/cfme-gemset/gems/activesupport-4.2.5/lib/active_support/notifications.rb:164:in `block in instrument'
/opt/rh/cfme-gemset/gems/activesupport-4.2.5/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
/opt/rh/cfme-gemset/gems/activesupport-4.2.5/lib/active_support/notifications.rb:164:in `instrument'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/action_controller/metal/instrumentation.rb:30:in `process_action'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
/opt/rh/cfme-gemset/gems/activerecord-4.2.5/lib/active_record/railties/controller_runtime.rb:18:in `process_action'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/abstract_controller/base.rb:137:in `process'
/opt/rh/cfme-gemset/gems/actionview-4.2.5/lib/action_view/rendering.rb:30:in `process'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/action_controller/metal.rb:196:in `dispatch'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/action_controller/metal.rb:237:in `block in action'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/action_dispatch/routing/route_set.rb:76:in `call'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/action_dispatch/routing/route_set.rb:76:in `dispatch'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/action_dispatch/routing/route_set.rb:45:in `serve'


Version-Release number of selected component (if applicable):
----------------------
5.5.0.11


How reproducible:
-----------------
Always


Steps to Reproduce:
------------------
1.Generate Policy events for a provider(For eg,on my appliance,I have defined this VM policy profile: Action taken - Tag VM for Event - VM Power on.So,every time a VM is powered on,the VM gets tagged.
2.View Policy events for the provider by navigating to the provider summary page,
clicking 'Monitoring' and then clicking 'Timelines'.On the Timelines page,
select 'Policy Events' in the Show option drop down.
3.Click any policy event.In the event bubble,click 'Assigned profiles'.


Actual results:
---------------
UI error


Expected results:
-----------------
No UI error


Additional info:
---------------