retry if nonce is invalid

fix https://github.com/Neilpang/acme.sh/issues/627

acme.sh

@@ -1530,6 +1530,10 @@ _send_signed_request() {
   payload64=$(printf "%s" "$payload" | _base64 | _url_replace)
   _debug3 payload64 "$payload64"
 
+  MAX_REQUEST_RETRY_TIMES=5
+  _request_retry_times=0
+  while [ "${_request_retry_times}" -lt "$MAX_REQUEST_RETRY_TIMES" ]; do
+    _debug3 _request_retry_times "$_request_retry_times" 
     if [ -z "$_CACHED_NONCE" ]; then
       _debug2 "Get nonce."
       nonceurl="$API/directory"
@@ -1570,15 +1574,15 @@ _send_signed_request() {
 
     response="$(_post "$body" "$url" "$needbase64")"
     _CACHED_NONCE=""
+
     if [ "$?" != "0" ]; then
       _err "Can not post to $url"
       return 1
     fi
     _debug2 original "$response"
-
     response="$(echo "$response" | _normalizeJson)"
 
-  responseHeaders="$(cat "$HTTP_HEADER")"
+    responseHeaders="$(< "$HTTP_HEADER")"
 
     _debug2 responseHeaders "$responseHeaders"
     _debug2 response "$response"
@@ -1587,6 +1591,15 @@ _send_signed_request() {
 
     _CACHED_NONCE="$(echo "$responseHeaders" | grep "Replay-Nonce:" | _head_n 1 | tr -d "\r\n " | cut -d ':' -f 2)"
 
+    if _contains "$response" "JWS has invalid anti-replay nonce"; then
+      _info "It seems the CA server is busy now, let's wait and retry."
+      _request_retry_times=$(_math "$_request_retry_times" + 1)
+      _sleep 5
+      continue
+    fi
+    break;
+  done
+
 }
 
 #setopt "file"  "opt"  "="  "value" [";"]