Stop mutating body response

If @app.call returns an object that is saved (for e.g., in a constant), the mutation results in a continuing cycle of wrapping the body in Rack::BodyProxy, eventually leading to SystemStackError
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On branch fix-return-response-mutation-rack-logger - Tue  3 Apr 2018 19:54:28 PDT by Geoff Lee <geoff.lee@lendesk.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/railties/lib/rails/rack/logger.rb b/railties/lib/rails/rack/logger.rb
index ec5212ee76..4ea7e40319 100644
--- a/railties/lib/rails/rack/logger.rb
+++ b/railties/lib/rails/rack/logger.rb
@@ -35,9 +35,9 @@ module Rails
           instrumenter = ActiveSupport::Notifications.instrumenter
           instrumenter.start "request.action_dispatch", request: request
           logger.info { started_request_message(request) }
-          resp = @app.call(env)
-          resp[2] = ::Rack::BodyProxy.new(resp[2]) { finish(request) }
-          resp
+          status, headers, body = @app.call(env)
+          body = ::Rack::BodyProxy.new(body) { finish(request) }
+          [status, headers, body]
         rescue Exception
           finish(request)
           raise