Right now, when the GitHub lister tries to use a set of credentials that are invalid (f.e. that are expired), it treats that as a transport error and sleeps 10 seconds.

This ends up being a 401 error with the content:

{
  "message": "Bad credentials",
  "documentation_url": "https://developer.github.com/v3"
}

It'd be better to:

• report the credentials issue instead of a generic transport error
• remove the credential from the set of credentials the worker is going to use
• retry the request with another credential immediately