Issue
When using heroku git:clone the output doesn't contain the latest updates/releases for the app.
Resolution
This occurs when deploys to your application started out with git push ... and have then switched to using our platform API, typically via the GitHub integration or other non-git push based deployment methods.
These API based deploys don't update the git repo for your app, which is one of the reasons we recommend using a dedicated service for source code management instead of relying on Heroku to store your git repo.
To get access to the latest code you can download the application slug using the Heroku Slugs plugin: https://github.com/heroku/heroku-slugs