Created attachment 924516 [details]
screen shot

Description of problem:

when I try to remove a deployment which has hosts assigned to it I get an error: 

Cannot delete record because it has descendants.

I think that this looks really bad from user prospective and we should be able to remove the hosts from the deployment when the user approves it. 
which is why I think we need to add a pop-up with a warning + approve/cancel operation. 

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

ruby193-rubygem-staypuft-0.1.22-1.el6ost.noarch

How reproducible:

100%

Steps to Reproduce:
1. create a new deployment and assign hosts to the deployment
2. try to remove the deployment 
3.

Actual results:

we get this error: 
Cannot delete record because it has descendants.

Expected results:

1. this looks like a UI crash 
2. we should be able to complete this action with user approval (detaching the hosts from the deployment ourselves) 

Additional info: look at screen shot - not very user friendly and looks like crash. 

Ancestry::AncestryException
Cannot delete record because it has descendants.
app/models/concerns/foreman/thread_session.rb:33:in `clear_thread'
lib/middleware/catch_json_parse_errors.rb:9:in `call'