update rrset only if existing challenge is found

dnsapi/dns_rcode0.sh

@@ -125,15 +125,20 @@ set_record() {
     _build_record_string "$oldchallenge"
   done
 
+  _debug "Challenges: $_existing_challenges"
+
+  if [ -z "$_existing_challenges" ]; then
     if ! _rcode0_rest "PATCH" "/api/v1/acme/zones/$root/rrsets" "[{\"changetype\": \"add\", \"name\": \"$full.\", \"type\": \"TXT\", \"ttl\": $RCODE0_TTL, \"records\": [$_record_string]}]"; then
       _err "Set txt record error."
      return 1
     fi
+  else
     # try update in case a records exists (need for wildcard certs)
     if ! _rcode0_rest "PATCH" "/api/v1/acme/zones/$root/rrsets" "[{\"changetype\": \"update\", \"name\": \"$full.\", \"type\": \"TXT\", \"ttl\": $RCODE0_TTL, \"records\": [$_record_string]}]"; then
       _err "Set txt record error."
       return 1
    fi
+  fi
 
   if ! notify_slaves "$root"; then
     return 1