Jinja templates can't import files outside template directory or subdirectory

Problem

I can't include files under templates/include/ directory from a template under template/scripts/ directory.

Actually, the build script sandbox the template in it's own directory.

This limit the includes to things in the same directory:

{%- include "./foo.jinja" %}

or in any subdirectory:

{%- include "./foo/bar.jinja" %}

Proposition

Passing several template directories

The jinja2.FileSystemLoader support a list of directory where to load templates:

A list of paths can be given. The directories will be searched in order, stopping at the first matching template.

We should at least add the templates/include/ directory.

Anchoring the template search path to the root

Another option could be to root the jinja2.FileSystemLoader to the top level templates/ directory, making includes working with full path:

{%- include "include/bar.jinja" %}
{%- include "scripts/quuux.jinja" %}