Use shared credentials with Bitbucket repository

I like the Shared Credentials functionality.

However, it requires you to create source repositories as type "Git" instead of "Bitbucket", to be able to select the shared credentials.

It would be much easier if I could choose between user/pass and shared credentials when adding a Bitbucket source repo to a plan. I'm wondering though if it is possible to load the list of repositories without having a bitbucket user/pass...