Proposal on improving "func shouldRetry(err error)"

[chainone]

I am thinking, for http errors, we may be able to check the status code to see if the request is retry-able. We have no reason to retry a request with status code 400, 403, 404.

However, as we have so many http status codes, it may be hard to check every code to tell if it is retry-able or not. I could not find any document about those http codes that are not retry-able.

Let me know if you have any comments, thanks.

[denverdino]

I agree. We need some revisit for the shouldRetry impl