output error info for debugging
output error info for debugging

jglascoe/heroku-buildpack-ruby-jekyll,mattmanning/heroku-buildpack-ruby-jekyll,mattmanning/heroku-buildpack-ruby-jekyll,lyoshenka/heroku-buildpack-ruby-jekyll,jglascoe/heroku-buildpack-ruby-jekyll,hausdorff/heroku-buildpack-ruby-jekyll,lyoshenka/heroku-buildpack-ruby-jekyll,darron/heroku-buildpack-ruby-jekyll,hausdorff/heroku-buildpack-ruby-jekyll,darron/heroku-buildpack-ruby-jekyll