Function index_with 

pub async fn index_with(
    root: &Path,
    src: &Path,
    repo: &str,
    view: &str,
    filter: &IndexFilter,
) -> Result<IndexSummary>

index, with control over which paths enter the view.

filter carries any --include overrides; the built-in vendored/generated rules and .gitignore apply either way (#209).