Serve blobs when a storage driver supports redirects but are disabled

Fixes issue where an error was returned instead of serving the blob

Signed-off-by: Brian Bland <brian.bland@docker.com>

registry/storage/blobserver.go

@@ -34,18 +34,22 @@ func (bs *blobServer) ServeBlob(ctx context.Context, w http.ResponseWriter, r *h
 		return err
 	}
 
+	if bs.redirect {
 		redirectURL, err := bs.driver.URLFor(ctx, path, map[string]interface{}{"method": r.Method})
-
 		switch err.(type) {
 		case nil:
-		if bs.redirect {
 			// Redirect to storage URL.
 			http.Redirect(w, r, redirectURL, http.StatusTemporaryRedirect)
 			return err
-		}
 
 		case driver.ErrUnsupportedMethod:
 			// Fallback to serving the content directly.
+		default:
+			// Some unexpected error.
+			return err
+		}
+	}
+
 	br, err := newFileReader(ctx, bs.driver, path, desc.Size)
 	if err != nil {
 		return err
@@ -71,8 +75,4 @@ func (bs *blobServer) ServeBlob(ctx context.Context, w http.ResponseWriter, r *h
 
 	http.ServeContent(w, r, desc.Digest.String(), time.Time{}, br)
 	return nil
-	}
-
-	// Some unexpected error.
-	return err
 }