## Impacted versions:
 8.0 / 9.0 / 10.0
## Steps to reproduce:
* see https://github.com/odoo/odoo/issues/11841
* in a shell
  1. create an in memory record `order = self.env['purcahse.order'].new({....})`
  2. create an in memory record with a reference to the first one `order_line = self.env['purchase.order.line'].new({'order_id': order, ....})`
  3. order_line.order_id is an in memory recordset
  4. create a record for a model that inherits from mail.thread `self.env['product.product'].create({....})`
  5. At this stage order_line.order_id is an empty recordset

## Current behavior:
 In memory records are dropped when a call is done to self.invalidate_cache
## Expected behavior:
In memory records are preserved when a call is done to self.invalidate_cache


There are lot of places where the method `invalidate_cache` is called and the silent removal of the in memory records from all environments has unpredictable effects on fields modified by a computed method or an onchange or even related fields .... Moreover since all caches are invalidated each time you create / write / unlink  (https://github.com/odoo/odoo/blob/10.0/addons/mail/models/mail_followers.py#L111) an instance of a model that inherits from 'mail.thread', the performances of the server are severely penalized.

OPW703903

addons/purchase/purchase.py
return True
    def onchange_pricelist(self, cr, uid, ids, pricelist_id, context=None):
        if not pricelist_id:
            return {}
        return {'value': {'currency_id': self.pool.get('product.pricelist').browse(cr, uid, pricelist_id, context=context).currency_id.id}}
    
    def onchange_dest_address_id(self, cr, uid, ids, address_id, context=None):
        if not address_id:
            return {}
        address = self.pool.get('res.partner')
        values = {}
        supplier = address.browse(cr, uid, address_id, context=context)
        if supplier:
            location_id = supplier.property_stock_customer.id
            values.update({'location_id': location_id})
        return {'value':values}
    def onchange_picking_type_id(self, cr, uid, ids, picking_type_id, context=None):
        value = {}
        if picking_type_id:
            picktype = self.pool.get("stock.picking.type").browse(cr, uid, picking_type_id, context=context)
            if picktype.default_location_dest_id:
                value.update({'location_id': picktype.default_location_dest_id.id, 'related_usage': picktype.default_location_dest_id.usage})
            value.update({'related_location_id': picktype.default_location_dest_id.id})
        return {'value': value}
    def onchange_location_id(self, cr, uid, ids, location_id, context=None):