Add fast-path for Listing with ResourceVersion=0

pkg/storage/watch_cache.go

@@ -283,11 +283,14 @@ func (w *watchCache) waitUntilFreshAndBlock(resourceVersion uint64, trace *util.
 
 // WaitUntilFreshAndList returns list of pointers to <storeElement> objects.
 func (w *watchCache) WaitUntilFreshAndList(resourceVersion uint64, trace *util.Trace) ([]interface{}, uint64, error) {
+	// If resourceVersion == 0 we'll return the data that we currently have in cache.
+	if resourceVersion != 0 {
 		err := w.waitUntilFreshAndBlock(resourceVersion, trace)
 		defer w.RUnlock()
 		if err != nil {
 			return nil, 0, err
 		}
+	}
 	return w.store.List(), w.resourceVersion, nil
 }