fix logic to not test ancientness of nonexistent sessions
fix logic to not test ancientness of nonexistent sessions

goofwear/letsencrypt,brentdax/letsencrypt,lmcro/letsencrypt,rlustin/letsencrypt,martindale/letsencrypt,beermix/letsencrypt,mrb/letsencrypt,DavidGarciaCat/letsencrypt,stweil/letsencrypt,skynet/letsencrypt,riseofthetigers/letsencrypt,jmhodges/letsencrypt,Sveder/letsencrypt,jmaurice/letsencrypt,beermix/letsencrypt,diracdeltas/lets-encrypt-preview,ghyde/letsencrypt,lmcro/letsencrypt,DavidGarciaCat/letsencrypt,VladimirTyrin/letsencrypt,luorenjin/letsencrypt,dietsche/letsencrypt,Jonadabe/letsencrypt,ahojjati/letsencrypt,jmhodges/letsencrypt,ghyde/letsencrypt,BillKeenan/lets-encrypt-preview,sjerdo/letsencrypt,lbeltrame/letsencrypt,brentdax/letsencrypt,wteiken/letsencrypt,skynet/letsencrypt,BillKeenan/lets-encrypt-preview,PeterMosmans/letsencrypt,jtl999/certbot,luorenjin/letsencrypt,Bachmann1234/letsencrypt,hsduk/lets-encrypt-preview,armersong/letsencrypt,BKreisel/letsencrypt,ruo91/letsencrypt,kuba/letsencrypt,tyagi-prashant/letsencrypt,deserted/letsencrypt,stewnorriss/letsencrypt,Sveder/letsencrypt,tdfischer/lets-encrypt-preview,sapics/letsencrypt,dietsche/letsencrypt,Hasimir/letsencrypt,mitnk/letsencrypt,twstrike/le_for_patching,kevinlondon/letsencrypt,thanatos/lets-encrypt-preview,armersong/letsencrypt,wteiken/letsencrypt,stewnorriss/letsencrypt,digideskio/lets-encrypt-preview,g1franc/lets-encrypt-preview,thanatos/lets-encrypt-preview,modulexcite/letsencrypt,ruo91/letsencrypt,jsha/letsencrypt,martindale/letsencrypt,bestwpw/letsencrypt,bsmr-misc-forks/letsencrypt,rlustin/letsencrypt,vcavallo/letsencrypt,Jadaw1n/letsencrypt,solidgoldbomb/letsencrypt,letsencrypt/letsencrypt,fmarier/letsencrypt,xgin/letsencrypt,riseofthetigers/letsencrypt,VladimirTyrin/letsencrypt,modulexcite/letsencrypt,Bachmann1234/letsencrypt,kevinlondon/letsencrypt,BKreisel/letsencrypt,piru/letsencrypt,ahojjati/letsencrypt,fmarier/letsencrypt,jmaurice/letsencrypt,tyagi-prashant/letsencrypt,rutsky/letsencrypt,twstrike/le_for_patching,g1franc/lets-encrypt-preview,solidgoldbomb/letsencrypt,bsmr-misc-forks/letsencrypt,mrb/letsencrypt,Jadaw1n/letsencrypt,vcavallo/letsencrypt,rugk/letsencrypt,bestwpw/letsencrypt,rutsky/letsencrypt,Jonadabe/letsencrypt,PeterMosmans/letsencrypt,mitnk/letsencrypt,stweil/letsencrypt,hlieberman/letsencrypt,sjerdo/letsencrypt,digideskio/lets-encrypt-preview,jsha/letsencrypt,xgin/letsencrypt,tdfischer/lets-encrypt-preview,lbeltrame/letsencrypt,diracdeltas/lets-encrypt-preview,kuba/letsencrypt,letsencrypt/letsencrypt,goofwear/letsencrypt,Hasimir/letsencrypt,hlieberman/letsencrypt,sapics/letsencrypt,rugk/letsencrypt,jtl999/certbot,TheBoegl/letsencrypt,deserted/letsencrypt,hsduk/lets-encrypt-preview,piru/letsencrypt,TheBoegl/letsencrypt