Merged r12985 (#14298).

git-svn-id: http://svn.redmine.org/redmine/branches/2.5-stable@13019 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/controllers/watchers_controller.rb

@@ -55,6 +55,9 @@ class WatchersController < ApplicationController
       user_ids = params[:watcher][:user_ids] || [params[:watcher][:user_id]]
       @users = User.active.where(:id => user_ids).all
     end
+    if @users.blank?
+      render :nothing => true
+    end
   end
 
   def destroy

test/functional/watchers_controller_test.rb

@@ -237,6 +237,13 @@ class WatchersControllerTest < ActionController::TestCase
     end
   end
 
+  def test_append_without_user_should_render_nothing
+    @request.session[:user_id] = 2
+    xhr :post, :append, :project_id => 'ecookbook'
+    assert_response :success
+    assert response.body.blank?
+  end
+
   def test_remove_watcher
     @request.session[:user_id] = 2
     assert_difference('Watcher.count', -1) do