[IMP] mail: Return a browse record in _track_subtype instead of xmlid

Purpose
=======

- A manager could want to follow only home working of its own department
- A HR officer could want to follow only sick leaves of all dpts.

We have to improve what people follow and how they follow it in the leaves module

Specifications
==============

Subtype on department
---------------------

In department form view, right now, people can follow approvals

Instead we should have some generic and specific subtypes depending on the leave type

For instance, a HR Officer wants to follow only sick leaves and a manager only home working

Following mechanism
-------------------

Remove first / second approval subtype differences
if a leave type is not linked to a specific subtype, consider only classic
people follow it (employee and assigned HR people / manager)

Link leave type to subtypes, with some by default (i.e. home working, ...), not mandatory

When creating a leave type, link it to the department to be able to
activate the subtype for only one department.

closes odoo/odoo#27620

1 files changed, 1 insertions, 1 deletions

diff --git a/doc/reference/mixins.rst b/doc/reference/mixins.rst
index d8c976ddaaa..af06849b435 100644
--- a/doc/reference/mixins.rst
+++ b/doc/reference/mixins.rst
@@ -331,7 +331,7 @@ can override the ``_track_subtype()`` function:
                 # in cache
                 self.ensure_one()
                 if 'state' in init_values and self.state == 'confirmed':
-                    return 'my_module.mt_state_change'  # Full external id
+                    return self.env.ref('my_module.mt_state_change')
                 return super(BusinessTrip, self)._track_subtype(init_values)