Revert "Remove potentially expired tokens."

This reverts commit 9b7a5fc618.

This patch casues issues for cross-repo mounts
when user doesn't have credentials for source repo
and fallback needs to happen.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

util/resolver/authorizer.go

@@ -405,11 +405,6 @@ func (ah *authHandler) fetchToken(ctx context.Context, sm *session.Manager, g se
 }
 
 func invalidAuthorization(c auth.Challenge, responses []*http.Response) error {
-	lastResponse := responses[len(responses)-1]
-	if lastResponse.StatusCode == http.StatusUnauthorized {
-		return errors.Wrapf(docker.ErrInvalidAuthorization, "authorization status: %v", lastResponse.StatusCode)
-	}
-
 	errStr := c.Parameters["error"]
 	if errStr == "" {
 		return nil