Import OS-specific vars in tasks instead of play

Something seems to have happened as of Ansible 2.4.0.0 where this no
longer works. I suspect it is related to the major changes to static
and dynamic imports that landed around this same time.

We make sure that this tasks always runs by using the special tag of
the same name.

roles/common/tasks/main.yml

@@ -1,5 +1,10 @@
 ---
 
+# ported from top-level play because it stopped working around Ansible 2.4.0.0
+- name: Import OS-specific variables
+  include_vars: "vars/{{ ansible_os_family }}.yml"
+  tags: always
+
 - name: Configure network time
   import_tasks: ntp.yml
   tags: ntp

web.yml

@@ -13,6 +13,5 @@
     - { role: munin, when: ansible_os_family == 'Debian' }
   vars_files:
     - vars/ipsets.yml
-    - "vars/{{ ansible_os_family }}.yml"
 
 # vim: set sw=2 ts=2: