Merge branch 'master' into glitch-soc/merge-upstream

Conflicts:
- `app/controllers/application_controller.rb`:
  Conflict due to theming system.
- `app/controllers/oauth/authorizations_controller.rb`:
  Conflict due to theming system.

app/controllers/auth/registrations_controller.rb

@@ -11,6 +11,7 @@ class Auth::RegistrationsController < Devise::RegistrationsController
   before_action :set_instance_presenter, only: [:new, :create, :update]
   before_action :set_body_classes, only: [:new, :create, :edit, :update]
   before_action :require_not_suspended!, only: [:update]
+  before_action :set_cache_headers, only: [:edit, :update]
 
   skip_before_action :require_functional!, only: [:edit, :update]
 
@@ -114,4 +115,8 @@ class Auth::RegistrationsController < Devise::RegistrationsController
   def require_not_suspended!
     forbidden if current_account.suspended?
   end
+
+  def set_cache_headers
+    response.headers['Cache-Control'] = 'no-cache, no-store, max-age=0, must-revalidate'
+  end
 end