Heroku + gunicorn not working (bash: gunicorn: command not found )

Question

I successfully install gunicorn:

remote: -----> Removing .DS_Store files
remote: -----> Python app detected
remote: -----> Installing dependencies with pip
remote:        Collecting gunicorn==19.0.0 (from -r requirements.txt (line 1))
remote:          Downloading gunicorn-19.0.0.tar.gz (382kB)
remote:        Installing collected packages: gunicorn
remote:          Running setup.py install for gunicorn
remote:        Successfully installed gunicorn-19.0.0

My Procfile:

web: gunicorn myapp:app --log-file=-

But the app crashes when deployed:

bash: gunicorn: command not found 

I tried adding the heroku python buildpack, but no luck. If I roll back to a previous commit (where requirements.txt and Procile are both unchanged), it works:

heroku/web.1:  Starting process with command `gunicorn myapp:app --log-file=-` 
app/web.1:  2015-10-08 17:04:18 [3] [INFO] Listening at: http://0.0.0.0:51854 (3)

Answer 1

The issue seemed to fix itself after uninstalling all requirements remotely, and reinstalling them.