async fn discover_dependencies_with_backtracking(
root_id: &PackageId,
root: &PackageInfo,
source: &dyn Source,
) -> Result<Option<DiscoveredPackages>, ResolveError>async fn discover_dependencies_with_backtracking(
root_id: &PackageId,
root: &PackageInfo,
source: &dyn Source,
) -> Result<Option<DiscoveredPackages>, ResolveError>