Make sure the reset role can be run with --check

We need to compute what mountpoints would be unmounted even when running with
--check

Signed-off-by: Julien DOCHE <julien.doche@gmail.com>

roles/reset/tasks/umount_with_children.yml

@@ -6,6 +6,7 @@
     executable: /bin/bash
   failed_when: false
   changed_when: get_mounted_filesystems.stdout | length > 0
+  check_mode: false
 
 - name: Umount filesystem
   mount: