disable annoying rails assets log messages

config/initializers/quite_assets.rb

@@ -0,0 +1,13 @@
+if Rails.env.development?
+  Rails.application.assets.logger = Logger.new('/dev/null')
+  Rails::Rack::Logger.class_eval do
+    def call_with_quiet_assets(env)
+      previous_level = Rails.logger.level
+      Rails.logger.level = Logger::ERROR if env['PATH_INFO'] =~ %r{^/assets/}
+      call_without_quiet_assets(env)
+    ensure
+      Rails.logger.level = previous_level
+    end
+    alias_method_chain :call, :quiet_assets
+  end
+end