fix test_perform_failure
fix test_perform_failure

lmcro/letsencrypt,jtl999/certbot,letsencrypt/letsencrypt,mitnk/letsencrypt,brentdax/letsencrypt,jsha/letsencrypt,bsmr-misc-forks/letsencrypt,DavidGarciaCat/letsencrypt,dietsche/letsencrypt,wteiken/letsencrypt,bsmr-misc-forks/letsencrypt,jtl999/certbot,mitnk/letsencrypt,dietsche/letsencrypt,brentdax/letsencrypt,DavidGarciaCat/letsencrypt,stweil/letsencrypt,jsha/letsencrypt,wteiken/letsencrypt,letsencrypt/letsencrypt,lmcro/letsencrypt,stweil/letsencrypt