If you don't use a cache you're just begging for Let's Encrypt to ban you for a week due to duplicate certificate requests. Don't encourage users to get banned. Change-Id: Icf999c7f28817990bb45931d30692d4040c0ed71 Reviewed-on: https://go-review.googlesource.com/66550 Run-TryBot: Russ Cox <rsc@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Alex Vaghin <ddos@google.com>