Digest not generated after compiling assets - ruby-on-rails

Question

After executing rake assets:precompile in production environment it show a message saying
Generated non-digest assets in 485ms
I also tried rake assets:precompile:all, rake assets:precompile:primary but still it isn't generating digest for assets. Here's my production.rb file.
Gullak2::Application.configure do
# Settings specified here will take precedence over those in config/application.rb
# Code is not reloaded between requests
config.cache_classes = true
# Full error reports are disabled and caching is turned on
config.consider_all_requests_local = false
config.action_controller.perform_caching = true
# Disable Rails's static asset server (Apache or nginx will already do this)
config.serve_static_assets = false
# Compress JavaScripts and CSS
config.assets.compress = true
# Don't fallback to assets pipeline if a precompiled asset is missed
config.assets.compile = true
# Generate digests for assets URLs
config.assets.digest = true
config.assets.logger = Logger.new($stdout)
# Defaults to nil and saved in location specified by config.assets.prefix
# config.assets.manifest = YOUR_PATH
# Specifies the header that your server uses for sending files
config.action_dispatch.x_sendfile_header = "X-Sendfile" # for apache
# config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect' # for nginx
# Force all access to the app over SSL, use Strict-Transport-Security, and use secure cookies.
# config.force_ssl = true
# See everything in the log (default is :info)
# config.log_level = :debug
# Prepend all log lines with the following tags
# config.log_tags = [ :subdomain, :uuid ]
# Use a different logger for distributed setups
# config.logger = ActiveSupport::TaggedLogging.new(SyslogLogger.new)
# Use a different cache store in production
# config.cache_store = :mem_cache_store
# Enable serving of images, stylesheets, and JavaScripts from an asset server
# config.action_controller.asset_host = "http://assets.example.com"
# Precompile additional assets (application.js, application.css, and all non-JS/CSS are already added)
config.assets.precompile += %w( merchant.css merchant.js)
config.assets.initialize_on_precompile = false
# Disable delivery errors, bad email addresses will be ignored
# config.action_mailer.raise_delivery_errors = false
# Enable threaded mode
# config.threadsafe!
# Enable locale fallbacks for I18n (makes lookups for any locale fall back to
# the I18n.default_locale when a translation can not be found)
config.i18n.fallbacks = true
# Send deprecation notices to registered listeners
config.active_support.deprecation = :notify
end

Answer 1

Try the following code out :-
task non_digested: :environment do
assets = Dir.glob(File.join(Rails.root, 'public/assets/**/*'))
regex = /(-{1}[a-z0-9]{32}*\.{1}){1}/
assets.each do |file|
next if File.directory?(file) || file !~ regex
source = file.split('/')
source.push(source.pop.gsub(regex, '.'))
non_digested = File.join(source)
FileUtils.cp(file, non_digested)
end
end

Answer 2

It was my fault. I didn't look through the log generated by rake assets:precompile RAILS_ENV=production command. It generates assets twice. First it generates assets with digest and after that it generates the non-digested assets.
I was reading only the last message which said Generated non-digest assets