Impacted versions:
* 11.0

Steps to reproduce:
* Create company A
* Create company B
* Admin user with both companies but currently in company B
* Create Demo user only with company B
* Create fiscal position A to company A
* Create fiscal position B to company B
* Create vendor with fiscal position A with company A and the same vendor with fiscal position B in company B
* Create product and add the vendor created before
* Set like **Create a draft purchase order**
* Logging with Demo user
* Create sale order with one sale order line with route **make to order**
* Validate sale order

Current behavior:
The purchase order created by sale order has the fiscal position **company A**

Expected behavior:
The purchase order must have fiscal position **company B**
action = self.env.ref('purchase.purchase_order_action_generic')
        action_dict = action.read()[0]
        action_dict['res_id'] = self.purchase_id.id
        action_dict['target'] = 'current'
        return action_dict
class ProductTemplate(models.Model):
    _name = 'product.template'
    _inherit = 'product.template'
    @api.model
    def _get_buy_route(self):
        buy_route = self.env.ref('purchase.route_warehouse0_buy', raise_if_not_found=False)
        if buy_route:
            return buy_route.ids
        return []
    @api.multi
    def _purchase_count(self):