fixes Rails version for the stable API [ci skip]

Rakefile

@@ -47,7 +47,11 @@ task :install => :build do
 end
 
 desc "Generate documentation for the Rails framework"
-Rails::API::RepoTask.new('rdoc')
+if ENV['EDGE']
+  Rails::API::EdgeTask.new('rdoc')
+else
+  Rails::API::StableTask.new('rdoc')
+end
 
 desc 'Bump all versions to match version.rb'
 task :update_versions do

railties/lib/rails/api/task.rb

@@ -135,12 +135,20 @@ def component_root_dir(component)
       def api_dir
         'doc/rdoc'
       end
+    end
 
+    class EdgeTask < RepoTask
       def rails_version
         "master@#{`git rev-parse HEAD`[0, 7]}"
       end
     end
 
+    class StableTask < RepoTask
+      def rails_version
+        File.read('RAILS_VERSION').strip
+      end
+    end
+
     class AppTask < Task
       def component_root_dir(gem_name)
         $:.grep(%r{#{gem_name}[\w.-]*/lib\z}).first[0..-5]