I think this code could also get hit if you programmatically access a directory that's under the watch root but filtered out by it -- on a recursive-watcher platform you'll get notifications from the impl about it changing, since you forcibly created the entry it'll exist in the index and not bail early in `_handleExternalChange()`.  But even in that case where I think the code _runs_, it won't actually do anything since the entry will never let itself cache anything (`_isWatched()` checks the watch root filtering).

I'll file a cleanup bug about removing this mystery code at a later point in time...