By default the debian installer immediately configures and uses the Debian update and security repos.

This is the equivalent of issuing the following installer option: d-i apt-setup/services-select multiselect updates,security

This is never desirable when using Katello to provide content, and makes offline installations impossible.

By adding the following line to the presseed finish template, we can override this behaviour:

d-i apt-setup/services-select multiselect