Conditional _excludes by with Jinja block template?

[mogul]

I'm using Copier 9.7.1

I'm specifying the question manage_spaces like this:

manage_spaces:
  help: "Auto-manage cloud.gov spaces?"
  default: true
  type: bool

The first _excludes example in the docs here implies that it should be possible to use Jinja if blocks in a string to indicate which files should be excluded. Reproducing that for easy reference:

_exclude:
    - "{% if _copier_operation == 'update' -%}src/*_example.py{% endif %}"

And that works! Only one or the other set of files gets copied when I do this:

_exclude:
  # When managing an org's spaces, exclude the sandbox bootstrap files
  - "{% if manage_spaces == true %}bootstrap/sandbox.tf{% endif %}"
  - "{% if manage_spaces == true %}bootstrap/templates/sandbox_imports.tf.tftpl{% endif %}"
  # When using a sandbox, exclude the org bootstrap files and production-specific variables
  - "{% if manage_spaces != true %}bootstrap/org.tf{% endif %}"
  - "{% if manage_spaces != true %}bootstrap/templates/org_imports.tf.tftpl{% endif %}"
  - "{% if manage_spaces != true %}bootstrap/users.auto.tfvars{% endif %}"
  - "{% if manage_spaces != true %}production.tfvars{% endif %}"

Now I want to make that DRYer by following this dynamic choices example, which similarly implies that it should be possible to wrap a Jinja template around YAML structure. Reproducing here:

dependency_manager:
    type: str
    help: Which dependency manager do you use?
    choices: |
        {%- if language == "python" %}
        - poetry
        - pipenv
        {%- else %}
        - npm
        - yarn
        {%- endif %}

But this doesn't work:

_exclude: |
  {%- if manage_spaces == true %}
  # When managing an org's spaces, exclude the sandbox bootstrap files
  - bootstrap/sandbox.tf
  - bootstrap/templates/sandbox_imports.tf.tftpl
  {%- else %}
  # When using a sandbox, exclude the org bootstrap files and production-specific variables
  - bootstrap/org.tf
  - bootstrap/templates/org_imports.tf.tftpl
  - bootstrap/users.auto.tfvars
  - production.tfvars
  {%- endif %}

When I do this, none of these files are excluded.

I've been wracking my brain on this for hours. What am I missing?!

[pawamoy]

Choices are probably specially handled, while exclusions are not. That would be a feature request 🙂