Test repeated installation of the primary with DNS enabled and domain set
Test that a repeated installation of the primary with DNS enabled
will lead to a already installed message and not in "DNS zone X
already exists in DNS" in check_zone_overlap.
The error is only occuring if domain is set explicitly in the command
line installer as check_zone_overlap is used in the domain_name validator.
Reviewed-By: Christian Heimes <email@example.com>