Preparing to unpack .../varnish_4.0.3-1_amd64.deb ...
Unpacking varnish (4.0.3-1) ...
Processing triggers for systemd (225-1ubuntu9.1) ...
Processing triggers for ureadahead (0.100.0-19) ...
Processing triggers for man-db (2.7.4-1) ...
Setting up varnish (4.0.3-1) ...

Configuration file '/etc/default/varnish'
 ==> Modified (by you or by a script) since installation.
 ==> Package distributor has shipped an updated version.
   What would you like to do about it ?  Your options are:
    Y or I  : install the package maintainer's version
    N or O  : keep your currently-installed version
      D     : show the differences between the versions
      Z     : start a shell to examine the situation
 The default action is to keep your current version.
*** varnish (Y/I/N/O/D/Z) [default=N] ? 
Installing new version of config file /etc/default/varnishncsa ...
Installing new version of config file /etc/init.d/varnish ...
Installing new version of config file /etc/init.d/varnishlog ...
Installing new version of config file /etc/init.d/varnishncsa ...
Installing new version of config file /etc/logrotate.d/varnish ...

Configuration file '/etc/varnish/default.vcl'
 ==> Modified (by you or by a script) since installation.
 ==> Package distributor has shipped an updated version.
   What would you like to do about it ?  Your options are:
    Y or I  : install the package maintainer's version
    N or O  : keep your currently-installed version
      D     : show the differences between the versions
      Z     : start a shell to examine the situation
 The default action is to keep your current version.
*** default.vcl (Y/I/N/O/D/Z) [default=N] ? 
Job for varnish.service failed because the control process exited with error code. See "systemctl status varnish.service" and "journalctl -xe" for details.
invoke-rc.d: initscript varnish, action "start" failed.
dpkg: error processing package varnish (--configure):
 subprocess installed post-installation script returned error exit status 1