Resolve "external backup on borg"

Closes #40 (closed)

roles/ynh_backup/tasks/borgbackup.yml

@@ -58,7 +58,7 @@
     regexp: "# ssh_command: ssh -i ~/.ssh/id_ed25519"
     line: "{{ ynh_ssh_borg_command }}"
     state: present
-  when: ynh_borg_backup_remote_repo and ynh_ssh_borg_command
+  when: ynh_ssh_borg_command is defined
 
 
 - name: change archive name in "/etc/borgmatic/{{ borgmatic_config_name }}"