add allow subset
add allow subset

bsmr-misc-forks/letsencrypt,letsencrypt/letsencrypt,letsencrypt/letsencrypt,jsha/letsencrypt,stweil/letsencrypt,jtl999/certbot,stweil/letsencrypt,lmcro/letsencrypt,jtl999/certbot,bsmr-misc-forks/letsencrypt,lmcro/letsencrypt,jsha/letsencrypt