replace links to assets in static error pages with links to hashed asset pipeline assets

static_assets.rake

namespace :assets do
  desc 'Update the URIs for assets used in the static pages (e.g. 500.html)'
  task :update_static_pages => :environment do
    manifest_path = Rails.root.join('public', 'assets', 'manifest.yml')
    unless File.exists?(manifest_path.to_s)
      raise "Must run assets:precompile first"
    end
    manifest = YAML.load(manifest_path.read)
    %w[404 422 500 504 browser].each do |static_page|
      path = Rails.root.join('public', "#{static_page}.html")
      content = path.read
      manifest.each_pair do |base_value, hash_value|
        content.gsub!(base_value, hash_value)
      end
      File.open(path, 'w') do |file|
        file.write content
      end
    end
  end
end