Don't call_registered() on SystemExit
Don't call_registered() on SystemExit

dietsche/letsencrypt,lbeltrame/letsencrypt,BKreisel/letsencrypt,piru/letsencrypt,thanatos/lets-encrypt-preview,goofwear/letsencrypt,letsencrypt/letsencrypt,xgin/letsencrypt,sjerdo/letsencrypt,mitnk/letsencrypt,Sveder/letsencrypt,VladimirTyrin/letsencrypt,BillKeenan/lets-encrypt-preview,stweil/letsencrypt,jsha/letsencrypt,mrb/letsencrypt,hsduk/lets-encrypt-preview,hsduk/lets-encrypt-preview,wteiken/letsencrypt,mitnk/letsencrypt,TheBoegl/letsencrypt,g1franc/lets-encrypt-preview,ghyde/letsencrypt,sjerdo/letsencrypt,lbeltrame/letsencrypt,jtl999/certbot,brentdax/letsencrypt,letsencrypt/letsencrypt,jtl999/certbot,DavidGarciaCat/letsencrypt,kuba/letsencrypt,brentdax/letsencrypt,piru/letsencrypt,TheBoegl/letsencrypt,VladimirTyrin/letsencrypt,kuba/letsencrypt,jsha/letsencrypt,Sveder/letsencrypt,martindale/letsencrypt,lmcro/letsencrypt,bsmr-misc-forks/letsencrypt,lmcro/letsencrypt,BillKeenan/lets-encrypt-preview,martindale/letsencrypt,goofwear/letsencrypt,stweil/letsencrypt,wteiken/letsencrypt,xgin/letsencrypt,thanatos/lets-encrypt-preview,g1franc/lets-encrypt-preview,mrb/letsencrypt,twstrike/le_for_patching,twstrike/le_for_patching,dietsche/letsencrypt,DavidGarciaCat/letsencrypt,BKreisel/letsencrypt,ghyde/letsencrypt,bsmr-misc-forks/letsencrypt