AutoDeploy stalls at rollout.

Summary

The AutoDevops pipeline breaks in the AutoDeploy stage on gitlab.com.

What is the current bug behavior?

New user here, I hope this issue is in the correct place. I have a private project in a private group on which I'm trying to get AutoDevops going. It runs correctly until the AutoDeploy job, which turns unresponsive after the following log:Waiting for rollout to finish: 0 of 1 updated replicas are available.... It does not answer afterwards until the timeout is reached and breaks the job. On GCloud the Console lets me reach the pod's log, which loops every 5 minutes into the same messages:

Could not determine a reasonable value for WEB_CONCURRENCY.
This is likely due to running the Heroku NodeJS buildpack on a non-Heroku
platform.

WEB_CONCURRENCY has been set to 1. Please review whether this value is
appropriate for your application.

> viewer@1.0.0 start /app
> node index.js

(node index.js being my start script in a package.json).

I found that the AutoDevops template uses buildpacks from Heroku, so I've set a BUILDPACK_URL variable in the project to point to a CloudFoundry NodeJS buildpack. Still the logs remain identical.

Output of checks

This bug happens on GitLab.com