Default to dev/null if no log file is passed in
Default to dev/null if no log file is passed in

mattmanning/heroku-buildpack-ruby-jekyll,makifund/heroku-buildpack-ruby,orenyk/heroku-buildpack-ruby,instacart/heroku-buildpack-ruby,brightbytes/heroku-buildpack-ruby-without-assets-precompile,pilotcreative/heroku-buildpack-ruby,pilotcreative/heroku-buildpack-ruby,Scalingo/ruby-buildpack,andycroll/heroku-buildpack-jekyll,instacart/heroku-buildpack-ruby,makifund/heroku-buildpack-ruby,orenyk/heroku-buildpack-ruby,heroku/heroku-buildpack-ruby,jonseaberg/heroku-buildpack-turbo-sprockets,donnykurnia/heroku-buildpack-ruby,ericboehs/heroku-buildpack-ruby,zunda/heroku-buildpack-ruby,zunda/heroku-buildpack-ruby,andycroll/heroku-buildpack-jekyll,Genius/heroku-buildpack-ruby,Genius/heroku-buildpack-ruby,ericboehs/heroku-buildpack-ruby,brightbytes/heroku-buildpack-ruby-without-assets-precompile,jonseaberg/heroku-buildpack-turbo-sprockets,Scalingo/ruby-buildpack,heroku/heroku-buildpack-ruby,mattmanning/heroku-buildpack-ruby-jekyll,donnykurnia/heroku-buildpack-ruby