Fix discussion error popup on http request abort

common/static/coffee/src/discussion/views/discussion_thread_view.coffee

@@ -120,7 +120,9 @@ if Backbone?
           )
           @trigger "thread:responses:rendered"
           @loadedResponses = true
-        error: (xhr) =>
+        error: (xhr, textStatus) =>
+          return if textStatus == 'abort'
+
           if xhr.status == 404
             DiscussionUtil.discussionAlert(
               gettext("Sorry"),