Bug#569035: minor correction

[Andrew Engelbrecht]

Ok, so the command I mentioned to remove extra configuration files is
not sufficient by itself. First you need to remove the extra
configuration file manually, and then do:

sudo apt-get --reinstall install system-tools-backends

The --purge option is unnecessary. Also, there may be a more
effieceint way of updating the database, but I don't know it.

-Andrew