@BartPalmer and @AleksandarArabadjiev,
While I understand that a change in behavior is always confusing, I think you are asking us to explain an undocumented and unsupported behavior. The section on Enabling OAuth 2.0 (3LO) that explains how to register a client in the developer console explains:
- Enter the Callback URL. Set this to any URL that is accessible by the app. When you implement OAuth 2.0 (3LO) in your app (see next section), the redirect_uri must match this URL.
Is there a reason you can’t fix the OAuth client in the developer console so the URLs match?