Rails 5.2 changes which Cache-Control headers are returned
Rails 5.2 changes which Cache-Control headers are returned

- There's more information in an excellent comment at
  https://github.com/rails/rails/issues/ 32557#issuecomment-381305169, but
  in summary:
  - "The no-cache and the must-revalidate;max-age=0 directives are
    conflicting and only the most restrictive one gets applied."
  - This happened in https://github.com/rails/rails/pull/ 30367.

alphagov/transition,alphagov/transition,alphagov/transition