Jinja2 does not support "is not" operator.

stack/erp5/instance-zeo.cfg.in

@@ -62,7 +62,7 @@ ipv6 = {{ ipv6 }}
          cache_size,
          client_dict,
        ]) -%}
-{%     if tidstorage_dict is not None -%}
+{%     if tidstorage_dict != None -%}
 {%       do known_tid_storage_identifier_dict.__setitem__(
            (known_tid_storage_identifier_host, export_id), (
              storage_dict['path'],
@@ -109,7 +109,7 @@ path = ${directory:promises}/zeo-tunnel-{{ storage_family }}
 {%   set next_port = next_port + 1 -%}
 {% endfor -%}
 
-{% if tidstorage_dict is not None -%}
+{% if tidstorage_dict != None -%}
 [tidstorage]
 recipe = slapos.cookbook:tidstorage
 known-tid-storage-identifier-dict = {{ dumps(known_tid_storage_identifier_dict) }}