The idea is to avoid flushing the fields to fetch in method _read().
This delays UPDATE queries, and makes the prefetching mechanism simpler
and more effective.
We do this by not overwriting the cache values by the values fetched
from database. This simple idea allows to fetch more fields and more
records without having to care about pending computations and updates.
But it requires the cache consistency to be much more strict, because
nothing will "fix" the cache inconsistencies "by chance". And it also
requires pending updates to be present in cache.
Part-of: odoo/odoo#66938
Raphael Collet
a91cb08c5d