Fail2ban's documentation suggests that modifications to the main configuration be
done in a .local file instead of modificating the main fail2ban.conf file.

If upgrading from a previous version of the module, you will probably end up with both
files having the same content. This is pretty harmless, but can be confusing at first.
Changes to the fail2ban.local file will have precedence over those in fail2ban.conf
so no matter if you previously had a modified fail2ban.conf file, the new values will
be used.

This change modifies the previous behaviour of the module where the main configuration
file was overwritten, but ensures future compatibility with fail2ban.