[FIX] purchase: Don't auto subscribe recipients on mail composers
[FIX] purchase: Don't auto subscribe recipients on mail composers

Purpose
=======

During the refactoring of the purchase module something went wrong when overriding the 'send_mail' method.

The 'mail_post_autofollow' key should have been set into the context only for the purchase orders model.

See: https://github.com/odoo/odoo/commit/cb01be2#diff-fe8587929089e5fdb6c75687011b1c7eR822

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo