Q:

Rails ActionMailer template updates not taking effect

I'm making changes to a Rails site that I was not involved in creating.  This site has a form for new users to sign up, which generates an email to administrators who can approve the new account.
When the template for these emails is changed, the content of the generated emails does not change.  How do I get changes to the email template to take effect?
I'm new to Rails, so I might be missing something obvious.  I believe these are the relevant files:
app/mailers/user_mailer.rb
class UserMailer < ActionMailer::Base
  default from: 'webmaster'

  def new_user_notification_mailer(user, admin_email)
    @user = user
      mail(to: admin_email, subject: 'New User Registration')
  end
end

app/workers/send_new_user_notification_worker.rb
class SendNewUserNotificationWorker
  include Sidekiq::Worker

  def perform(user_id)
    user = User.find(user_id)
    if user
      User.is_admin.each do |admin|
        if admin.email
          UserMailer.new_user_notification_mailer(user, admin.email).deliver
        end
      end
    end
  end
end

app/views/user_mailer/new_user_notification_mailer.html.slim
doctype html
html
  head
    meta content='text/html; charset=UTF-8' http-equiv='Content-Type'
  body
    p
      | New user 
      b #{@user.first_name} #{@user.last_name}
      | has registered on the web site.
    | You can 
    = link_to "Manage", edit_admin_user_url(@user)
    | this account from admin panel.

I've been restarting the server (of the working copy) with this:
RAILS_ENV=production bash -c 'bundle exec rake assets:clean; bundle exec rake bower:resolve; bundle exec rake assets:precompile'; kill `cat tmp/pids/server.pid`; nohup bundle exec rails s -e production -p 4000 1>> log/rails.sever.log 2>> log/rails.server.err.log &

A:

You need to restart your sidekiq process also. It will re-load your rails environment and code changes for sidekiq process. After this, your changes should reflect.

