FIX: 'disable_edit_notifications' will only disable revisions made by the system user

app/models/post_alert_observer.rb

@@ -41,10 +41,10 @@ class PostAlertObserver < ActiveRecord::Observer
     post = post_revision.post
 
     return unless post
-    return if SiteSetting.disable_edit_notifications
     return if post_revision.user.blank?
     return if post_revision.user_id == post.user_id
     return if post.topic.private_message?
+    return if SiteSetting.disable_edit_notifications && post_revision.user_id == Discourse::SYSTEM_USER_ID
 
     alerter.create_notification(post.user, Notification.types[:edited], post, display_username: post_revision.user.username)
   end

spec/models/post_alert_observer_spec.rb

@@ -40,11 +40,23 @@ describe PostAlertObserver do
       }.should change(post.user.notifications, :count).by(1)
     end
 
-    it 'does not notifiy a user of the revision when edit notifications are disabled' do
+    context "edit notifications are disabled" do
-      SiteSetting.stubs(:disable_edit_notifications).returns(true)
+
+      before { SiteSetting.stubs(:disable_edit_notifications).returns(true) }
+
+
+      it 'notifies a user of the revision made by another user' do
         lambda {
           post.revise(evil_trout, "world is the new body of the message")
-      }.should_not change(post.user.notifications, :count).by(1)
+        }.should change(post.user.notifications, :count).by(1)
+      end
+
+      it 'does not notifiy a user of the revision made by the system user' do
+        lambda {
+          post.revise(Discourse.system_user, "world is the new body of the message")
+        }.should_not change(post.user.notifications, :count)
+      end
+
     end
 
   end