When attempting to use RepositoryFile resource with a branchSelector instead of branch, the value returned by the referenced object is the terraform ID of the branch resource, which unfortunately is not simply the branch name, but a repository_name:branch combination.
E.g.: my-repo:main instead of main .

This in turn causes an endless and confusing error in the RepositoryFile resource:

unexpected status code: 404 Not Found

Because the resource expects to receive only the branch name, using the branch field instead of branchSelector works.

I believe this can be fixed rather easily by using the Extractor option in the config.Reference object to let it know which field should be returned upon discovering the branch resource in branchSelector.