Hostgroup environment isn't inherited by Host via model API
Since [[hostgroup_inherited_attributes](https://github.com/theforeman/foreman/blob/develop/app/models/host/managed.rb#L577)] uses association IDs instead of AR objects, creating hosts like
hg.environment = Environment.first sample_host = Host.new(:name => 'hostname', :hostgroup => hg).environment sample_host.environment == nil #=> true
will not work.
The method to inherit these attributes relies on string attributes so Host must be created using 'hostgroup_id' or 'hostgroup_name' to inherit hostgroup attributes, like:
sample_host = Host.new(:name => 'hostname', 'hostgroup_id' => hg.id)
Make apply_inherited_attributes capable of inheriting regular AR relations, and not just attributes when passed as strings. That's why inheritance only works from the UI.