Comment 8 for bug 1475850

You are right about that one:

Preparing to unpack .../cron_3.0pl1-127ubuntu1_i386.deb ...
Unpacking cron (3.0pl1-127ubuntu1) over (3.0pl1-127ubuntu1) ...
Processing triggers for man-db (2.7.3-1) ...
Processing triggers for systemd (225-1ubuntu4) ...
Processing triggers for ureadahead (0.100.0-19) ...
Setting up cron (3.0pl1-127ubuntu1) ...
update-rc.d: warning: start and stop actions are no longer supported; falling back to defaults
update-rc.d: warning: stop runlevel arguments (1) do not match cron Default-Stop values (none)

Looks like its one of the non transitionned yet, the latest upgrade is quite old:

cron (3.0pl1-127ubuntu1) vivid; urgency=low

  * Merge from Debian unstable. Remaining changes:
    - debian/control:
      + Move MTA to Suggests field.
    - debian/cron.upstart: Add Upstart script.
    - debian/rules: Call dh_installinit to install Upstart job properly.
    - d/cron.default: change to a deprecated message to make it clear
      that the file is no longer in use.

 -- Michael Vogt <email address hidden> Mon, 27 Oct 2014 10:19:21 +0100