Fixed that requesting a message from an invalid forum should respond with 404 (#13232).

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11446 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/controllers/messages_controller.rb

@@ -125,7 +125,7 @@ class MessagesController < ApplicationController
 
 private
   def find_message
-    find_board
+    return unless find_board
     @message = @board.messages.find(params[:id], :include => :parent)
     @topic = @message.root
   rescue ActiveRecord::RecordNotFound
@@ -137,5 +137,6 @@ private
     @project = @board.project
   rescue ActiveRecord::RecordNotFound
     render_404
+    nil
   end
 end