Could you limit it to widely used libraries? e.g. browser ships with the last N versions of jQuery etc., and avoids the request if it's a known hash. If it's widely used, it seems like the amount of information leaked would be low, and if the browser _always_ ships with it (rather than caching on first use), it would only identify the browser and not browsing history anyway.

As a bonus, developers could use it knowing that there is much less likely to be a performance hit from fetching it.