Bug#476249: exim4-config: minimaldns does not work if no FQDN is configured in /etc/hosts

[Marc Haber]

Package: exim4-config
Version: 4.50-8
Severity: important

Minimaldns does not work if no FQDN is configured in /etc/hosts.

Minimaldns is implemented by hardcoding the output of hostname --fqdn
to the global primary_hostname configuration option at the time where
update-exim4.conf is executed. However, this only happens when the
output of hostname --fqdn contains at least one dot. If there is no
dot in hostname --fqdn's output, primary_hostname silently remains
unset even if the minimaldns config option is set, which causes DNS
lookups to occur on exim startup.

update-exim4.conf should print a warning if minimaldns is requested
but hostname --fqdn does not print an FQDN.

Lothar Ketterer spotted this and was very helpful in pinning down the
issue as I was seriously confused during the debugging process.

Greetings
Marc