Cloned from https://bugzilla.redhat.com/show_bug.cgi?id=1195637
Description of problem:

UI should report errors to the user when External AD UserGroup addition fails.

Processing by UsergroupsController#update as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"w4GDcBCBEdfi+TG0Lg7cPljNH4/96go+SS0giOfYNdY=", "usergroup"=>{"name"=>"foreman", "user_ids"=>["", "5", "", "4", "", "6", ""], "admin"=>"0", "role_ids"=>["", "11"], "external_usergroups_attributes"=>{"0"=>{"_destroy"=>"false", "name"=>"kedargrp", "auth_source_id"=>"4", "id"=>"8"}, "1"=>{"_destroy"=>"false", "name"=>"foobargroup", "auth_source_id"=>"3", "id"=>"7"}, "new_external_usergroups"=>{"_destroy"=>"false", "name"=>"", "auth_source_id"=>"3"}, "new_1424766851040"=>{"_destroy"=>"false", "name"=>"hdhdhd", "auth_source_id"=>"3"}}}, "id"=>"3-foreman"}
Failed to save: Name is not found in the authentication source

OR

Processing by UsergroupsController#update as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"w4GDcBCBEdfi+TG0Lg7cPljNH4/96go+SS0giOfYNdY=", "usergroup"=>{"name"=>"foreman", "user_ids"=>["", "5", "", "4", "", "6", ""], "admin"=>"0", "role_ids"=>["", "11"], "external_usergroups_attributes"=>{"0"=>{"_destroy"=>"false", "name"=>"kedargrp", "auth_source_id"=>"4", "id"=>"8"}, "1"=>{"_destroy"=>"false", "name"=>"foobargroup", "auth_source_id"=>"3", "id"=>"7"}, "new_external_usergroups"=>{"_destroy"=>"false", "name"=>"", "auth_source_id"=>"3"}, "new_1424767137133"=>{"_destroy"=>"false", "name"=>"foobargroup", "auth_source_id"=>"3"}}}, "id"=>"3-foreman"}
Failed to save: Name has already been taken

Version-Release number of selected component (if applicable):
sat6.1 Beta snap3

How reproducible:

Steps to Reproduce:
1. create usergroup
2. add an invalid external AD UserGroup.
3.

Actual results:
No error message seen on the UI.

foreman/production.log shows

a) "Failed to save: Name is not found in the authentication source"
b) Failed to save: Name has already been taken

Expected results:
Shouls display the actual error on the UI,
a) "Name is not found in the authentication source"
b) Name has already been taken

Additional info: