ruby-on-rails - Heroku cedar で RUBY を実行できない

Question

「heroku run ...」を実行しても、常に次のエラーが発生します。

/usr/bin/env: ruby​​1.9.1: そのようなファイルやディレクトリはありません

次のように：

user@box:~/path$ heroku run rake db:migrate
Running `rake db:migrate` attached to terminal... up, run.7070
/usr/bin/env: ruby1.9.1: No such file or directory

バージョンは次のとおりです。

user@box:~/path$ heroku run ruby -v
Running `ruby -v` attached to terminal... up, run.8039
ruby 1.9.3p448 (2013-06-27 revision 41675) [x86_64-linux]

これが私のGemfileです

source 'https://rubygems.org'

gem 'rails', '4.0.0'

ruby "1.9.3"

gem 'rails_12factor'

gem 'pg'

group :production do
  gem 'therubyracer-heroku',  '0.8.1.pre3'
end

# Use SCSS for stylesheets
gem 'sass-rails', '~> 4.0.0'

# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'

# Use CoffeeScript for .js.coffee assets and views
gem 'coffee-rails', '~> 4.0.0'

# See https://github.com/sstephenson/execjs#readme for more supported runtimes
# gem 'therubyracer', platforms: :ruby

# Use jquery as the JavaScript library
gem 'jquery-rails'

gem 'turbolinks'

gem 'jbuilder', '~> 1.2'

group :doc do
  # bundle exec rake doc:rails generates the API under doc/api.
  gem 'sdoc', require: false
end