Fix building ZFS on linux.

ansible/roles/zfs/tasks/linux.yaml

@@ -4,6 +4,20 @@
       - linux-lts-headers
     state: present
 
+- name: Check trusted gpg keys
+  become_user: "{{ build_user.name }}"
+  command: gpg --list-public-keys --keyid-format LONG
+  register: gpgkeys
+  changed_when: false
+  check_mode: no
+
+- name: Trust ZFS key
+  when: "item not in gpgkeys.stdout"
+  become_user: "{{ build_user.name }}"
+  command: "gpg --recv-key '{{ item }}'"
+  loop:
+    - "0AB9E991C6AF658B"
+
 - name: Build aur packages
   register: buildaur
   become_user: "{{ build_user.name }}"