rake assets:precompile stuck while deployment after adding rufus-scheduler?

I seem to have the same problem as rake assets:precompile stuck but there's no real solution except for removing rufus-scheduler again.

So, I've installed rufus-scheduler and added this test scheduler

require 'rufus-scheduler'

scheduler = Rufus::Scheduler.new

scheduler.every '5s' do
  puts 'Test1'
end

scheduler.join

and when I deploy, it gets stuck here:

00:16 deploy:assets:precompile
  01 ls /home/user/my-app/releases/20170915094411/assets_manifest_backup
  01 ls: cannot access /home/user/my-app/releases/20170915094411/assets_manifest_backup: No such file or directory
  02 ~/.rvm/bin/rvm ruby-2.3.1@my-app do bundle exec rake assets:precompile
  02 Resque::Helpers will be gone with no replacement in Resque 2.0.0.
  02 /home/essteam/.rvm/rubies/ruby-2.3.1/bin/ruby /home/user/my-app/shared/bundle/ruby/2.3.0/bin/rake assets:precompile:all RAILS_ENV=production RAILS_GROUPS=assets
  02 Resque::Helpers will be gone with no replacement in Resque 2.0.0.
  02 Resque::Helpers will be gone with no replacement in Resque 2.0.0.
  02 Test1
  02 Test1