Give the user some warning before enabling backports
Give the user some warning before enabling backports

lmcro/letsencrypt,bsmr-misc-forks/letsencrypt,VladimirTyrin/letsencrypt,DavidGarciaCat/letsencrypt,dietsche/letsencrypt,twstrike/le_for_patching,bsmr-misc-forks/letsencrypt,stweil/letsencrypt,jtl999/certbot,stweil/letsencrypt,dietsche/letsencrypt,brentdax/letsencrypt,mitnk/letsencrypt,thanatos/lets-encrypt-preview,TheBoegl/letsencrypt,kuba/letsencrypt,jsha/letsencrypt,lmcro/letsencrypt,brentdax/letsencrypt,mitnk/letsencrypt,jtl999/certbot,letsencrypt/letsencrypt,twstrike/le_for_patching,kuba/letsencrypt,DavidGarciaCat/letsencrypt,jsha/letsencrypt,TheBoegl/letsencrypt,letsencrypt/letsencrypt,VladimirTyrin/letsencrypt,wteiken/letsencrypt,thanatos/lets-encrypt-preview,wteiken/letsencrypt