Temporarily commented out the substitution of the tarball
includes/DefaultSettings.php with the template for three reasons:
1) when switching from a MediaWiki version to a subsequent one the
DefaultSettings.php file may change significantly, as it was the case
between MediaWiki-1.22.8 and MediaWiki-1.23.1; using the old template
was not possible and caused the wiki aspect to not function properly
(missed menus and bars, etc). I specify the tarball externally in a
hiera file but then i had to change the template.
2) As strongly recommended at the beginning of the DefaultSettings.php
file, it should not be edited. It is intended to contain all the default
settings, specific for that version of the MediaWiki. All wiki specific
settings should be done in the LocalSettings.php file.
3) More importantly, it caused problems when one has more than one wiki
instance if he specifies slightly different settings in different
instances (I had different values for the smtp_idhost parameter because
I wanted to use the wiki instance name as part of the sender address).
One could move the SMTP settings from the mediawiki::instance define to
the mediawiki class, hence ensuring the SMTP parameters are not messed
up between different wiki instances (but remains the problem of the
template when upgrading the MediaWiki software) or leave them in the
mediawiki::instance define and writing them in the LocalSettings.php
file by using a mechanism different from the template, for example by
using the puppetlabs-inifile module or the file_line resource from
stdlib.