0.7.2: --keep-going not working as expected

We recently had a problem of certificates not renewed, despite running a cron every day. Looking at the issue, we found that one of the lines in `domains.txt` (in the middle of the file) is for a virtual host no longer hosted on the server, leading to an error when trying to check/renew this certificate.

We tried to add `--keep-going` to the cron command or `KEEP_GOING=yes` in the config file but none helps. `dehydrated` continues to stop after the certificate causing the error. Am I wrong to assume that it should continue?

Start by reproducing the cron scenario with a domains.txt entry for a virtual host no longer hosted on the server. Compare --keep-going with KEEP_GOING=yes in the configuration and verify that processing continues after the failed certificate instead of stopping.

Written by the indexing model from the issue text.