Do not raise an error if bin/rails was already removed

Author: alindeman

Rakefile

@@ -51,7 +51,7 @@ namespace :generate do
       bindir = File.expand_path("bin")
 
       # Rails 4 cannot use a `rails` binstub generated by Bundler
-      sh "rm #{bindir}/rails"
+      sh "rm -f #{bindir}/rails"
       sh "bundle exec rails new ./tmp/example_app --skip-javascript --skip-gemfile --skip-git --skip-test-unit"
 
       if test ?d, bindir