Merge pull request #2501 from Neilpang/dev

fix HEAD request against the new LE CDN.

README.md

@@ -1,6 +1,6 @@
 # An ACME Shell script: acme.sh [![Build Status](https://travis-ci.org/Neilpang/acme.sh.svg?branch=master)](https://travis-ci.org/Neilpang/acme.sh)
 
-[![Join the chat at https://gitter.im/acme-sh/Lobby](https://badges.gitter.im/acme-sh/Lobby.svg)](https://gitter.im/acme-sh/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+<img src="https://opencollective.com/acmesh/tiers/backers/badge.svg?label=backer&color=brightgreen" /> [![Join the chat at https://gitter.im/acme-sh/Lobby](https://badges.gitter.im/acme-sh/Lobby.svg)](https://gitter.im/acme-sh/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 - An ACME protocol client written purely in Shell (Unix shell) language.
 - Full ACME protocol implementation.
 - Support ACME v1 and ACME v2

acme.sh

@@ -1697,6 +1697,9 @@ _post() {
     if [ "$HTTPS_INSECURE" ]; then
       _CURL="$_CURL --insecure  "
     fi
+    if [ "$httpmethod" = "HEAD" ]; then
+      _CURL="$_CURL -I  "
+    fi
     _debug "_CURL" "$_CURL"
     if [ "$needbase64" ]; then
       if [ "$_postContentType" ]; then