Fix #4680: @-ing yourself sends you a DMail.

Don't send a dmail when the user @-mentions themselves, whether in an
edit or in the original message.

app/logical/concerns/mentionable.rb

@@ -28,12 +28,14 @@ module Mentionable
     text_was = send(:attribute_before_last_save, message_field)
 
     names = DText.parse_mentions(text) - DText.parse_mentions(text_was)
+    users = names.map { |name| User.find_by_name(name) }.uniq
+    users = users.without(CurrentUser.user)
 
-    names.uniq.each do |name|
-      body  = self.instance_exec(name, &self.class.mentionable_option(:body))
-      title = self.instance_exec(name, &self.class.mentionable_option(:title))
+    users.each do |user|
+      body  = self.instance_exec(user.name, &self.class.mentionable_option(:body))
+      title = self.instance_exec(user.name, &self.class.mentionable_option(:title))
 
-      Dmail.create_automated(to_name: name, title: title, body: body)
+      Dmail.create_automated(to: user, title: title, body: body)
     end
   end
 end

test/unit/forum_post_test.rb

@@ -60,6 +60,12 @@ class ForumPostTest < ActiveSupport::TestCase
           EOS
         end
       end
+
+      should "not send a mention to yourself" do
+        assert_no_difference("Dmail.count") do
+          @forum_post = as(@user) { create(:forum_post, body: "hi from @#{@user.name}") }
+        end
+      end
     end
 
     context "that belongs to a topic with several pages of posts" do