Fixes usage message when running rails without --dev on a cloned rails repo

railties/lib/rails/generators/base.rb

@@ -3,7 +3,7 @@
 rescue LoadError
   puts "Thor is not available.\nIf you ran this command from a git checkout " \
        "of Rails, please make sure thor is installed,\nand run this command " \
-       "as `ruby /path/to/rails new myapp --dev`"
+       "as `ruby #{$0} #{ARGV.join(" ")} --dev`"
   exit
 end