flag for preseeding hostname

defaults/main.yml

@@ -1,3 +1,4 @@
 debian_installer_method: false
 debian_installer_directory: host_files/{{ inventory_hostname }}/debian-installer
+debian_installer_set_hostname: true
 debian_installer_nonfree_firmware: false

templates/preseed.cfg.j2

@@ -18,7 +18,9 @@ d-i network-console/password-disabled boolean true
 {% endif %}
 
 ### Hostname
+{% if debian_installer_set_hostname %}
 d-i netcfg/hostname string {{inventory_hostname}}
+{% endif %}
 
 ### Mirror settings
 d-i mirror/country string manual