revocation: don't fail if certificate already has been revoked (fixes #236)
revocation: don't fail if certificate already has been revoked (fixes #236)

Rayne/letsencrypt.sh,ahnooie/dehydrated,lukas2511/letsencrypt.sh,dennisschuerholz/dehydrated,erorus/letsencrypt.sh,lukas2511/dehydrated