Ensure show exceptions middleware properly filters backtrace before logging.

actionpack/lib/action_dispatch/middleware/show_exceptions.rb

@@ -135,7 +135,7 @@ def log_error(exception)
         ActiveSupport::Deprecation.silence do
           message = "\n#{exception.class} (#{exception.message}):\n"
           message << exception.annoted_source_code if exception.respond_to?(:annoted_source_code)
-          message << exception.backtrace.join("\n  ")
+          message << "  " << application_trace(exception).join("\n  ")
           logger.fatal("#{message}\n\n")
         end
       end

railties/test/application/middleware_test.rb

 require 'isolation/abstract_unit'
+require 'stringio'
 
 module ApplicationTests
   class MiddlewareTest < Test::Unit::TestCase
@@ -163,6 +164,25 @@ def index
       assert_equal "1.1.1.1", remote_ip("REMOTE_ADDR" => "4.2.42.42,1.1.1.1")
     end
 
+    test "show exceptions middleware filter backtrace before logging" do
+      my_middleware = Struct.new(:app) do
+        def call(env)
+          raise "Failure"
+        end
+      end
+
+      make_basic_app do |app|
+        app.config.middleware.use my_middleware
+      end
+
+      stringio = StringIO.new
+      Rails.logger = Logger.new(stringio)
+
+      env = Rack::MockRequest.env_for("/")
+      Rails.application.call(env)
+      assert_no_match(/action_dispatch/, stringio.string)
+    end
+
     private
 
       def boot!