Merge branch 'rails5-fix-6607' into 'master'

Rails5 fix NoMethodError: undefined method `join' for "":String

Closes #6607

See merge request gitlab-org/gitlab-ee!6278

ee/changelogs/unreleased/rails5-fix-6607.yml

+---
+title: 'Rails5 fix NoMethodError: undefined method `join'' for "":String'
+merge_request: 6278
+author: Jasper Maes
+type: fixed

ee/spec/controllers/oauth/applications_controller_spec.rb

@@ -15,7 +15,7 @@ describe Oauth::ApplicationsController do
         sign_in(user)
 
         application = build(:oauth_application)
-        application_attributes = application.attributes.merge(scopes: [])
+        application_attributes = application.attributes.merge("scopes" => [])
 
         expect { post :create, doorkeeper_application: application_attributes }.to change { SecurityEvent.count }.by(1)
       end