Touch file with git revision when freezing edge

railties/lib/tasks/framework.rake

@@ -43,9 +43,12 @@ namespace :rails do
       require 'open-uri'
       version = ENV["RELEASE"] || "edge"
       target  = "rails_#{version}.zip"
+      commits = "http://github.com/api/v1/yaml/rails/rails/commits/master"
       url     = "http://dev.rubyonrails.org/archives/#{target}"
 
       chdir 'vendor' do
+        latest_revision = YAML.load(open(commits))["commits"].first["id"]
+
         puts "Downloading Rails from #{url}"
         File.open('rails.zip', 'wb') do |dst|
           open url do |src|
@@ -61,6 +64,8 @@ namespace :rails do
         %w(rails.zip rails/Rakefile rails/cleanlogs.sh rails/pushgems.rb rails/release.rb).each do |goner|
           rm_f goner
         end
+
+        touch "rails/REVISION_#{latest_revision}"
       end
 
       puts 'Updating current scripts, javascripts, and configuration settings'