Capistrano 3 deploy notification email with git diff

Capfile

require 'mail'

deploy.rb

namespace :deploy do
  task :notify do                                                                                                                                                                                                
  
    Mail.defaults do                                                                                                                                                                                             
      delivery_method :smtp, address: "smtp.foo.com", port: 25                                                                                                                                                  
    end       
    
    current_revision = fetch :current_revision                                                                                                                                                                   
    previous_revision = fetch :previous_revision                                                                                                                                                                 
    log = ""                                                                                                                                                                                                     
    on roles(:web) do                                                                                                                                                                                            
      within release_path do                                                                                                                                                                                     
        log = capture("cd #{repo_path} && git --no-pager log --pretty=\"format:%h - %s (%ar) <%an>\" #{previous_revision}..#{current_revision}")                                                                 
      end                                                                                                                                                                                                            
    end                                                                                                                                                                                                          
  
    Mail.deliver do                                                                                                                                                                                              
      from    "deploy@foo.com"                                                                                                                                                                   
      to      "team@foo.com"                                                                                                                                                                      
      subject "Deploy Notification #{current_revision} (#{fetch :stage})"                                                                                                                                                 
      body    "Current Revision #{current_revision}\nPrevious Revision: #{previous_revision}\n\n#{log}"                                                                                                          
    end  
  end
end

Gemfile

gem 'mail'