In the NGINX configuration we generate, we're redirecting _all_ HTTP
requests to HTTPS, when HTTPS is enabled. But the HTTP-01 challenge
works on port 80 and is getting redirected to 443.
This usually fine, as Let's Encrypt respects that redirect and completes
the challenge on port 443. But, if port 443 is blocked to outside
access, the cert renewal will fail. This PR fixes that.
Tested on a server with port 80 open and 443 closed to outside Internet.
Cert renewal fails without this PR's changes, and works with this PR's
changes.
e6ca21c34a