fix test failure

cmd/notary/tuf.go

@@ -884,7 +884,7 @@ func tokenAuth(trustServerURL string, baseTransport *http.Transport, gun data.GU
 	if endpoint.Scheme == "" {
 		return nil, fmt.Errorf("Trust server url has to be in the form of http(s)://URL:PORT. Got: %s", trustServerURL)
 	}
-	subPath, err := url.Parse(path.Join(endpoint.Path, "/v2/"))
+	subPath, err := url.Parse(path.Join(endpoint.Path, "/v2") + "/")
 	if err != nil {
 		return nil, fmt.Errorf("Failed to parse v2 subpath. This error should not have been reached. Please report it as an issue at https://github.com/docker/notary/issues: %s", err.Error())
 	}