Merge commit 'a32a126cac42c73236236b5a9bd660765b9c58ee' into glitch-soc/merge-upstream

Conflicts:
- `spec/lib/sanitize/config_spec.rb`:
  Conflict due to glitch-soc having factored the file differently.
  Ported upstream's changes.

app/controllers/application_controller.rb

@@ -131,7 +131,7 @@ class ApplicationController < ActionController::Base
   end
 
   def single_user_mode?
-    @single_user_mode ||= Rails.configuration.x.single_user_mode && Account.where('id > 0').exists?
+    @single_user_mode ||= Rails.configuration.x.single_user_mode && Account.without_internal.exists?
   end
 
   def use_seamless_external_login?