[Clients] Jinja expressions relying on multiple attributes not rendered properly when one of them is removed

[Boris-INSA]

This bug only affects clients that contain Jinja expressions that rely on multiple attributes from the server.

Example client configuration whose maildisplayname attribute is composed based on the values of displayname and primaryaffiliation:

hermes-client:
  # (...)
  datamodel:
    Users:
      # (...)
      attrsmapping:
        # (...)
        maildisplayname: "{{ (displayname ~ ' (STUDENT)') if (primaryaffiliation|default('')) == 'student' else displayname }}"
        # (...)

This bug occurs only in modified events: maildisplaynamewill be generated correctly unless primaryaffiliation is deleted, in which case it will be deleted as well instead of just having the value of displayname.

[Boris-INSA]

FIX GUIDE

If your clients are likely to be impacted, here are the steps to fix invalid values (proceed on each client):

1. Edit the client's config file, and in each data-type declared and maybe impacted, insert a non-significant space into the Jinja expression : e.g. replace {{ attr1 ~ attr2 }} by {{ attr1 ~ attr2 }}. This simple change will trigger a datamodel update on the next client startup, which will recalculate the values of all Jinja expressions and propagate the new (good) values if they differ from the previous ones.
2. Restart your client.