test of basic middleman heroku app with ruby 1.9.3

middleman_heroku_app.sh

# create an app
heroku auth:whoami
app_name=$(perl -ne 'print $1 if m/^Creating ([\w\-]+)\.\.\./' <(heroku create))
echo "created app_name=$app_name"
echo "destroy with"
echo "heroku destroy --app $app_name --confirm $app_name"
#
heroku config:set --app $app_name BUILDPACK_URL=https://github.com/ddollar/heroku-buildpack-multi.git
# per https://devcenter.heroku.com/articles/ruby-versions#migration
heroku config:set --app $app_name PATH=bin:vendor/bundle/ruby/1.9.1/bin:/usr/local/bin:/usr/bin:/bin
heroku config --app $app_name -s | grep PATH
heroku run --app $app_name "ruby -v"

# create content
cd ~
middleman init $app_name --rack
cd $app_name
perl -i.bak -pe 's/^(source.*)$/$1\n\nruby "1.9.3"/' Gemfile
echo 'web: bundle exec thin start -p $PORT' > Procfile
cat -- > .buildpacks <<EOF
https://github.com/heroku/heroku-buildpack-ruby.git
https://github.com/hashicorp/heroku-buildpack-middleman.git
EOF

# bundle install and create repo
source ~/.rvm/scripts/rvm
bundle install
git init
git add .
git commit -a -m 'initial commit'
heroku git:remote -a $app_name

# make sure you can push to heroku
keyfile=~/.ssh/id_rsa
if [[ ! -f $keyfile ]]; then
        ssh-keygen -t rsa -P "" -f $keyfile
fi
heroku keys:add $keyfile.pub

# push
git push heroku master
# results in following error
# =====> Downloading Buildpack: https://github.com/hashicorp/heroku-buildpack-middleman.git
# =====> Detected Framework: Middleman
# Your Ruby version is 1.9.2, but your Gemfile specified 1.9.3
# 
#  !     Push rejected, failed to compile Multipack app