Thanks so much for reporting this issue! We were able to reproduce it.
It seems the error is related with a tool, ini-file, we're using to manipulate ini configuration files. This tool has a bug and it doesn't respect the original file permissions. We're working on having a fix for this ASAP.
In the meantime, you can workaround the issue by running the command below:
sudo chown -R couchdb:couchdb /opt/bitnami/couchdb/etc/
We will notify you as soon as we release a new version of the CouchDB single VM addressing this issue.