Heroku Ruby Buildpack检测失败

Question

我正在尝试部署我的Ruby on Rails应用程序，该应用程序当前位于分支"rails_app“上(如下所示)。我之前已经成功地部署了它，但它现在不能使用额外的更改。当我通过运行"heroku buildpack“手动查找构建包时，它表明正确的构建包在那里。当我尝试重新安装构建包时，当我尝试推送到heroku时，它也显示它已经在那里了，我收到了检测设置构建路径失败的消息，如下所示。

Dougs-MBP-2:Rails_Application Doug$ heroku buildpacks
app_name Buildpack URL
heroku/ruby
Dougs-MBP-2:Rails_Application Doug$ git branch
gh-pages
master
* rails_app
update
Dougs-MBP-2:Rails_Application Doug$ git push heroku rails_app:master
Counting objects: 70, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (70/70), done.
Writing objects: 100% (70/70), 217.85 KiB | 0 bytes/s, done.
Total 70 (delta 46), reused 0 (delta 0)
remote: Compressing source files... done.
remote: Building source:
remote: 
remote: -----> Failed to detect set buildpack https://codon-buildpacks.s3.amazonaws.com/buildpacks/heroku/ruby.tgz
remote: More info: https://devcenter.heroku.com/articles/buildpacks#detection-failure
remote: 
remote:  !     Push failed
remote: Verifying deploy...
remote: 
remote: !   Push rejected to app_name.
remote: 
To https://git.heroku.com/app_name.git
! [remote rejected] rails_app -> master (pre-receive hook declined)
error: failed to push some refs to 'https://git.heroku.com/app_name.git'

谢谢你的帮助。