module ActiveSupport::Dependencies

def self.search_for_file(relpath)

Private method used by require_dependency.
def self.search_for_file(relpath)
  relpath += ".rb" unless relpath.end_with?(".rb")
  autoload_paths.each do |autoload_path|
    abspath = File.join(autoload_path, relpath)
    return abspath if File.file?(abspath)
  end
  nil
end