How do I find the source of a Rails 3 "Deprecation Warning"?

I'm getting a deprecation warning from Rails 3 in development.log as follows:

DEPRECATION WARNING: Calling a meth开发者_开发技巧od in Rails::Application is deprecated, please call it directly in your application constant MyApp::Application. (called from ... config/environment.rb:5)

When I go to config/environment.rb, I get this:

MyApp::Application.initialize!

Presumably this line is not the problem. I found something similar here, which seems to require exchanging Rails.Application for MyApp::Application - but I already have the latter.

Is there any way to determine what is triggering this warning?

Sure thing - here is what config/environment.rb looks like:

# Load the rails application
require File.expand_path('../application', __FILE__)

# Initialize the rails application
MyApp::Application.initialize!