UI is sending an extra attribute in the parameter hash being passed to Tower. Tower actually successfully updated the corresponding project.  The error is at Ansible Tower ruby client at here https://github.com/ansible/ansible_tower_client_ruby/blob/c9e742fedde3308f4391bd315cd02029bd425371/lib/ansible_tower_client/base_model.rb#L88-L88

If you are able to perform a refresh, you will see the description is updated. (We seems don't expose refresh trigger in UI for this embedded Ansible. So what I did is trigger the refresh in rails console)

Here is the debug log I generated:
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[----] I, [2017-03-30T16:28:05.233456 #18450:34f134]  INFO -- : MIQ(ManageIQ::Providers::EmbeddedAnsible::AutomationManager::ConfigurationScriptSource#update_in_provider) update_in_provider {"name"=>"jamestest", "description"=>"noway-done", "scm_type"=>"git", "manager_resource"=>{"href"=>"https://10.8.99.124/api/providers/1"}, "scm_url"=>"https://github.com/testrepo/playbooks", "authentication_id"=>nil, "scm_branch"=>"", "scm_clean"=>false, "scm_delete_on_update"=>false, "scm_update_on_launch"=>false, "href"=>"https://10.8.99.124/api/configuration_script_sources/1", "id"=>1, "manager_id"=>1, "manager_ref"=>"6", "created_at"=>"2017-03-30T17:53:31Z", "updated_at"=>"2017-03-30T20:21:54Z", "type"=>"ManageIQ::Providers::EmbeddedAnsible::AutomationManager::ConfigurationScriptSource", "actions"=>[{"name"=>"edit", "method"=>"post", "href"=>"https://10.8.99.124/api/configuration_script_sources/1"}, {"name"=>"delete", "method"=>"post", "href"=>"https://10.8.99.124/api/configuration_script_sources/1"}, {"name"=>"delete", "method"=>"delete", "href"=>"https://10.8.99.124/api/configuration_script_sources/1"}]}

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The `manager_resource` is what ansible tower client is calling fault at

@Harpreet/@Zita, please take a look.

https://github.com/ManageIQ/manageiq-ui-classic/pull/899