This patch fixes a bug where a user specifies a v1 mirror for --registry-mirror and pull an image from the Hub. It used to not fallback because of an unexpected error returned when trying to JSON marshal nginx output. We now ensure that any unexpected error falls back to the next endpoint in the list. Signed-off-by: Tibor Vass <tibor@docker.com> Upstream-commit: a21ba12f4e7f11c17e6d665716f3060b9923b11c Component: engine