Merge pull request #29967 from naw/binstub-error-msg

Improve bundler binstub error message

railties/lib/rails/app_loader.rb

@@ -8,15 +8,26 @@ module AppLoader # :nodoc:
     RUBY = Gem.ruby
     EXECUTABLES = ["bin/rails", "script/rails"]
     BUNDLER_WARNING = <<EOS
-Looks like your app's ./bin/rails is a stub that was generated by Bundler.
+Beginning in Rails 4, Rails ships with a `rails` binstub at ./bin/rails that
+should be used instead of the Bundler-generated `rails` binstub.
 
-In Rails #{Rails::VERSION::MAJOR}, your app's bin/ directory contains executables that are versioned
-like any other source code, rather than stubs that are generated on demand.
+If you are seeing this message, your binstub at ./bin/rails was generated by
+Bundler instead of Rails.
 
-Here's how to upgrade:
+You might need to regenerate your `rails` binstub locally and add it to source
+control:
+
+ rails app:update:bin           # Bear in mind this generates other binstubs
+                                # too that you may or may not want (like yarn)
+
+If you already have Rails binstubs in source control, you might be
+inadverently overwriting them during deployment by using bundle install
+with the --binstubs option.
+
+If your application was created prior to Rails 4, here's how to upgrade:
 
   bundle config --delete bin    # Turn off Bundler's stub generator
-  rails app:update:bin          # Use the new Rails 5 executables
+  rails app:update:bin          # Use the new Rails executables
   git add bin                   # Add bin/ to source control
 
 You may need to remove bin/ from your .gitignore as well.