Merge commit '877090518682b6c77ba9bdfa0231afd56daec44d' into glitch-soc/merge-upstream

Conflicts:
- `app/models/concerns/user/has_settings.rb`:
  Not a real conflict, upstream added a setting textually close to a glitch-soc one.
  Added upstream's new setting.
- `app/views/settings/preferences/appearance/show.html.haml`:
  Not a real conflict, upstream added a setting textually close to a glitch-soc one.
  Added upstream's new setting.
- `config/routes.rb`:
  Upstream moved web app routes to `config/routes/web_app.rb`, while glitch-soc had
  an extra route.
  Moved the extra route to `config/routes/web_app.rb`.
- `spec/controllers/settings/preferences/appearance_controller_spec.rb`:
  This spec got converted to a system spec upstream.
  However, the theme setting works differently in glitch-soc, so the spec had been
  changed.
  Changed the corresponding system spec as well.

lib/tasks/db.rake

@@ -43,8 +43,14 @@ namespace :db do
   end
 
   task pre_migration_check: :environment do
-    version = ActiveRecord::Base.connection.database_version
-    abort 'This version of Mastodon requires PostgreSQL 12.0 or newer. Please update PostgreSQL before updating Mastodon.' if version < 120_000
+    pg_version = ActiveRecord::Base.connection.database_version
+    abort 'This version of Mastodon requires PostgreSQL 12.0 or newer. Please update PostgreSQL before updating Mastodon.' if pg_version < 120_000
+
+    schema_version = ActiveRecord::Migrator.current_version
+    abort <<~MESSAGE if ENV['SKIP_POST_DEPLOYMENT_MIGRATIONS'] && schema_version < 2023_09_07_150100
+      Zero-downtime migrations from Mastodon versions earlier than 4.2.0 are not supported.
+      Please update to Mastodon 4.2.x first or upgrade by stopping all services and running migrations without `SKIP_POST_DEPLOYMENT_MIGRATIONS`.
+    MESSAGE
   end
 
   Rake::Task['db:migrate'].enhance(['db:pre_migration_check'])

lib/tasks/mastodon.rake

@@ -592,7 +592,7 @@ namespace :mastodon do
 end
 
 def disable_log_stdout!
-  dev_null = Logger.new('/dev/null')
+  dev_null = Logger.new(File::NULL)
 
   Rails.logger                 = dev_null
   ActiveRecord::Base.logger    = dev_null