Incorporate review by @drybjed, thanks!

Author: ypid

CHANGES.rst

@@ -42,7 +42,7 @@ Changed
 ~~~~~~~
 
 - Change default virtual host server name from ``000-default`` to ``default.{{
-  apache__domain }}`` to increase the changes that a valid certificate is
+  apache__domain }}`` to increase the chances that a valid certificate is
   available for this virtual host (either wildcard or SAN) in order to avoid
   the warning of Apache that the certificate is not valid for the server name. [ypid_]
 

defaults/main.yml

@@ -74,7 +74,7 @@ apache__fqdn: '{{ ansible_local.core.fqdn
 apache__domain: '{{ ansible_local.core.domain
                     if (ansible_local|d() and ansible_local.core|d() and
                         ansible_local.core.domain|d())
-                    else ansible_domain }}'
+                    else (ansible_domain if ansible_domain else ansible_hostname) }}'
 
                                                                    # ]]]
 # .. envvar:: apache__config_path [[[