Comment 3 for bug 1970187

Also quoting from https://docs.docker.com/registry/spec/auth/token/

  token
  An opaque Bearer token that clients should supply to subsequent
  requests in the Authorization header.

  access_token
  For compatibility with OAuth 2.0, we will also accept token under
  the name access_token. At least one of these fields must be
  specified, but both may also appear (for compatibility with older
  clients). When both are specified, they should be equivalent; if
  they differ the client's choice is undefined.

All other fields are optional whereas at least one of token or
access_token has to be present and they have to be same if both are.
So I think an easy fix would be as demonstrated in attached patch,
though it doesn't touch unit tests at all.