Deploy fails when uploading Pipfile.lock

[ddahan]

When I deploy my project with Pipfile and Pipfile.lock, here is the error I got on Heroku:

-----> Python app detected
-----> Installing dependencies with Pipenv 11.8.2…
       Your Pipfile.lock (48bdc8) is out of date. Expected: (2bfadf).
       Aborting deploy.
 !     Push rejected, failed to compile Python app.
 !     Push failed

Note that my Pipfile.lock is up to date since I ran pipenv update just before commiting, pushing and deploying.

If I erase my Pipfile.lock, then commiting, pushing, deploying, it works.
However, it's not a clean solution because the Pipfile.lock must be updated to ensure deterministic builds.

I'm using Python 3.6.5 and Pipenv 2018.05.18.
Not sure why the buildpack hardcoded the 11.8.2 version.

[sigmavirus24]

Related to #701

[CaseyFaist]

Buildpack is currently pinned at Pipenv version 2018.05.18, and will be updated as stable releases come out 👍