Avoid prompting for GitHub OAuth token when dist install authentication fails

I have basic auth implemented on top of my Satis server, since I'm using it to serve packages that I sell access to. However, when my auth returns a 401 Unauthorized error, instead of the package install failing right then, Composer tries to download the source from GitHub, and since the source repository is private, prompts the user for a GitHub OAuth token.

Is there some way to prevent this? It's a bit confusing for the end user.

Thanks for all your work on Satis and Composer!