DPKG error processing package

In my case, I got a 'Error while processing package hostname'. But hostname was not actually the problem here.
When dpkg (through apt-get) processes packages, it leaves some intermediate files in /var/lib/dpkg/info/<package-name>.postinst
Those file are then executed if you run 'apt-get install -f'.
For example, my hostname.postinst did some checking and was running this command : 'update-rc.d hostname.sh defaults > /dev/null'.
As the output was redirected to /dev/null, I could not see where the problem was.

The next step was to run 'sudo update-rc.d hostname.sh defaults' which yielded a more useful error message: 'Script virtuoso-nepomuk is broken: missing end of LSB comment'.

Indeed, this script was missing a part. Its comment section should begin with '### BEGIN INIT INFO' and end with '### END INIT INFO' (which was missing).

Now 'apt-get install -f' is running fine again (until the next bug).

References:
https://askubuntu.com/questions/654951/failed-to-connect-to-socket-com-ubuntu-upstart-connection-refused-errors-were
https://superuser.com/questions/242304/script-script-name-is-broken-missing-end-of-lsb-comment