FIX: ensure we have no dangling db connections on threads

This correct 10 second timeouts in dev mode, when reloader kicks in

config/application.rb

@@ -210,6 +210,9 @@ module Discourse
       # Load plugins
       Discourse.plugins.each(&:notify_after_initialize)
 
+      # we got to clear the pool in case plugins connect
+      ActiveRecord::Base.connection_handler.clear_active_connections!
+
       # This nasty hack is required for not precompiling QUnit assets
       # in test mode. see: https://github.com/rails/sprockets-rails/issues/299#issuecomment-167701012
       ActiveSupport.on_load(:action_view) do

lib/scheduler/defer.rb

@@ -74,6 +74,8 @@ module Scheduler
       end
     rescue => ex
       Discourse.handle_job_exception(ex, message: "Processing deferred code queue")
+    ensure
+      ActiveRecord::Base.connection_handler.clear_active_connections!
     end
   end
 

plugins/discourse-narrative-bot/plugin.rb

@@ -32,7 +32,7 @@ after_initialize do
   ].each { |path| load File.expand_path(path, __FILE__) }
 
   # Disable welcome message because that is what the bot is supposed to replace.
-  SiteSetting.send_welcome_message = false
+  SiteSetting.send_welcome_message = false if SiteSetting.send_welcome_message
 
   require_dependency 'plugin_store'