## 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

for po in self.browse(cr, uid, ids, context=context):
            is_invoiced = []
            if po.invoice_method == 'picking':
                
                
                
                
                
                for po_line in po.order_line:
                    if (po_line.move_ids and
                            all(move.state in ('done', 'cancel') for move in po_line.move_ids) and
                            not all(move.state == 'cancel' for move in po_line.move_ids) and
                            all(move.invoice_state == 'invoiced' for move in po_line.move_ids if move.state == 'done')
                            and po_line.invoice_lines and all(line.invoice_id.state not in ['draft', 'cancel'] for line in po_line.invoice_lines)):
                        is_invoiced.append(po_line.id)
                    elif po_line.product_id.type == 'service':
                        is_invoiced.append(po_line.id)
            else:
                for po_line in po.order_line:
                    if (po_line.invoice_lines and 
                            all(line.invoice_id.state not in ['draft', 'cancel'] for line in po_line.invoice_lines)):
                        is_invoiced.append(po_line.id)
            if is_invoiced:
                self.pool['purchase.order.line'].write(cr, uid, is_invoiced, {'invoiced': True})
            workflow.trg_write(uid, 'purchase.order', po.id, cr)
class purchase_order_line(osv.osv):
    def _calc_line_base_price(self, cr, uid, line, context=None):