Bug#481660: exim4-base: Exim refuses to start due to empty arguments

Package: exim4-base
Version: 4.69-2+b1
Severity: important
File: /etc/init.d/exim4

I did a 'dpkg-reconfigure exim4-config' to change my smarthost and was
give this message in return:

  Stopping MTA for restart:.
  Restarting MTA:exim: incompatible command-line options or arguments
  invoke-rc.d: initscript exim4, action "restart" failed.

Running 'EX4DEBUG=1 invoke-rc.d exim4 start' reveals that Exim is
started with:

  /sbin/start-stop-daemon --start --nicelevel 0 --quiet --exec
  /usr/sbin/exim4 --oknodo --pidfile /var/run/exim4/exim.pid -- -bd
  -q30m '' '' ''

where the final three empty arguments cause the trouble. If I run the
command without them Exim starts.

They come from three empty variables used in /etc/init.d/exim4:

  start_daemon -p "$PIDFILE" \
    "$DAEMON" -bd "-q${QFLAGS}${QUEUEINTERVAL}" \
    "${COMMONOPTIONS}" "${QUEUERUNNEROPTIONS}" "${SMTPLISTENEROPTIONS}"

Since I don't think I have done anything special to make the variables
empty, I am afraid this problem might affect many users.