Retry when io.readAll fail

[chimerYuheng]

Hi, I recently learned how golang make http request:

1. send request
2. receive header containing io.reader
3. use io.reader to make follow-up request for the actual payload

I ran into a scenario where we failed on step 3 and did not see retry, and I am not really sure how to make it retryable with go-retryablehttp. Seems like this Do function isn't returning the actual payload directly.