heroku/rails_serve_static_assets — pull request #1 by patrickmcgraw (2013-08-14 21:00:57+00:00)
Title: Continue managing the x_sendfile_header setting.

I moved a Rails 3 app to Rails 4 and the configuration files were setting x_sendfile_header. I believe Heroku used to take care of setting this to nil. I think this change will help guarantee that folks who include this gem will have apps that actually serve static assets on Heroku.