Check cached sources with upstream after the cache TTL (closes #69) (#350)

internal/handlers/referer_blocklist_internal_test.go

@@ -36,10 +36,11 @@ type countingFetcher struct {
 // Fetch counts the fetch and passes it on.
 func (f *countingFetcher) Fetch(
 	ctx context.Context, source imagerequest.Source,
+	ifNoneMatch, ifModifiedSince string,
 ) (*httpfetcher.FetchResult, error) {
 	f.fetches.Add(1)
 
-	return f.Fetcher.Fetch(ctx, source)
+	return f.Fetcher.Fetch(ctx, source, ifNoneMatch, ifModifiedSince)
 }
 
 // newRefererRoutes returns both image routes of a Handlers whose