tasks: stop arch-svntogit.timer before rebooting

In a recent execution of the server upgrade task, svntogit was started
shortly before the reboot command was issued. Therefore, it was killed
two seconds into its run, leaving behind a lock file that prevented it
from starting again after gemini was rebooted.

Avoid the above timing issue by stopping the timer before rebooting.

playbooks/tasks/include/upgrade-server.yml

@@ -39,11 +39,6 @@
 
 - name: gemini pre-reboot checks
   block:
-    - name: wait for svntogit to finish
-      wait_for:
-        path: /srv/svntogit/update-repos.sh.lock
-        state: absent
-
     - name: list logged on users
       command: who
       register: who
@@ -53,6 +48,14 @@
       when:
         - who is changed
         - who.stdout_lines|length > 1
+
+    - name: stop arch-svntogit.timer
+      service: name=arch-svntogit.timer state=stopped
+
+    - name: wait for svntogit to finish
+      wait_for:
+        path: /srv/svntogit/update-repos.sh.lock
+        state: absent
   when: inventory_hostname == "gemini.archlinux.org"
 
 - name: reboot