Proxy body if it is fresh enough

In order to prevent response body resulting in race conditions.

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/rack/conditionalget.rb b/lib/rack/conditionalget.rb
index 2c2113f2..88573166 100644
--- a/lib/rack/conditionalget.rb
+++ b/lib/rack/conditionalget.rb
@@ -25,11 +25,13 @@ module Rack
         status, headers, body = @app.call(env)
         headers = Utils::HeaderHash.new(headers)
         if status == 200 && fresh?(env, headers)
-          body.close if body.respond_to? :close
           status = 304
           headers.delete('Content-Type')
           headers.delete('Content-Length')
-          body = []
+          original_body = body
+          body = Rack::BodyProxy.new([]) do
+            original_body.close if original_body.respond_to?(:close)
+          end
         end
         [status, headers, body]
       else