FIX: notifications inconsistencies + never notify system user

app/models/post_action.rb

@@ -188,7 +188,7 @@ class PostAction < ActiveRecord::Base
     return if staff_already_replied?(related_post.topic)
     message_key = "flags_dispositions.#{disposition}"
     message_key << "_and_deleted" if delete_post
-    related_post.topic.add_moderator_post(moderator, I18n.t(message_key), skip_notifications: true)
+    related_post.topic.add_moderator_post(moderator, I18n.t(message_key))
   end
 
   def staff_already_replied?(topic)

app/services/post_alerter.rb

@@ -10,14 +10,14 @@ class PostAlerter
   def after_create_post(post)
     if post.topic.private_message?
       # If it's a private message, notify the topic_allowed_users
-      post.topic.all_allowed_users.reject{ |user| user.id == post.user_id }.each do |user|
-        next if user.blank?
-
+      post.topic.all_allowed_users.reject do |user|
+        user.blank? ||
+        user.id == Discourse::SYSTEM_USER_ID ||
+        user.id == post.user_id
+      end.each do |user|
         if TopicUser.get(post.topic, user).try(:notification_level) == TopicUser.notification_levels[:tracking]
-          next unless post.reply_to_post_number
-          next unless post.reply_to_post.user_id == user.id
+          next unless post.reply_to_post_number || post.reply_to_post.user_id == user.id
         end
-
         create_notification(user, Notification.types[:private_message], post)
       end
     elsif post.post_type != Post.types[:moderator_action]
@@ -82,6 +82,7 @@ class PostAlerter
 
   def create_notification(user, type, post, opts={})
     return if user.blank?
+    return if user.id == Discourse::SYSTEM_USER_ID
 
     # Make sure the user can see the post
     return unless Guardian.new(user).can_see?(post)

lib/post_creator.rb

@@ -97,7 +97,7 @@ class PostCreator
 
     if @post && @post.errors.empty?
       publish
-      PostAlerter.post_created(@post) unless @opts[:import_mode] || @opts[:skip_notifications]
+      PostAlerter.post_created(@post) unless @opts[:import_mode]
 
       track_latest_on_category
       enqueue_jobs

spec/models/post_action_spec.rb

@@ -507,15 +507,6 @@ describe PostAction do
       expect(topic.posts.count).to eq(1)
     end
 
-    it "should not generate a notification for auto-message" do
-      post = create_post
-      PostAction.act(moderator, post, PostActionType.types[:spam], message: "WAT")
-
-      PostAlerter.expects(:post_created).never
-
-      PostAction.agree_flags!(post, admin)
-    end
-
   end
 
 end