There is a race condition between ARC and GitHub service about deleting runner pod.
- The ARC use REST API to find a particular runner in a pod that is not running any jobs, so it decides to delete the pod.
- A job is queued on the GitHub service side, and it sends the job to this idle runner right before ARC deletes the pod.
- The ARC delete the runner pod which cause the in-progress job to end up canceled.
To avoid this race condition, I am calling `r.unregisterRunner()` before deleting the pod.
- `r.unregisterRunner()` will return 204 to indicate the runner is deleted from the GitHub service, we should be safe to delete the pod.
- `r.unregisterRunner` will return 400 to indicate the runner is still running a job, so we will leave this runner pod as it is.
TODO: I need to do some E2E tests to force the race condition to happen.
Ref #911
0b9bef2c08