Including UrlFor in Redirecting and Head will warn usefully if a controller is wired up without a router included (and still support redirect_to "omg")

actionpack/lib/action_controller/metal/head.rb

@@ -2,6 +2,8 @@ module ActionController
   module Head
     extend ActiveSupport::Concern
 
+    include ActionController::UrlFor
+
     # Return a response that has no content (merely headers). The options
     # argument is interpreted to be a hash of header names and values.
     # This allows you to easily return a response that consists only of
@@ -24,9 +26,6 @@ module ActionController
       end
 
       self.status = status
-      # ROUTES TODO: Figure out how to rescue from a no method error
-      # This is needed only if you wire up a controller yourself, and
-      # this not working would be baffling without a better error
       self.location = url_for(location) if location
       self.content_type = Mime[formats.first]
       self.response_body = " "

actionpack/lib/action_controller/metal/redirecting.rb

@@ -12,6 +12,7 @@ module ActionController
 
     include AbstractController::Logger
     include ActionController::RackDelegation
+    include ActionController::UrlFor
 
     # Redirects the browser to the target specified in +options+. This parameter can take one of three forms:
     #
@@ -83,9 +84,6 @@ module ActionController
           raise RedirectBackError unless refer = request.headers["Referer"]
           refer
         else
-          # ROUTES TODO: Figure out how to rescue from a no method error
-          # This is needed only if you wire up a controller yourself, and
-          # this not working would be baffling without a better error
           url_for(options)
         end.gsub(/[\r\n]/, '')
       end