The option can be used to force pre 1.6 style SELECT on save behaviour.
This is needed in case the database returns zero updated rows even if
there is a matching row in the DB. One such case is PostgreSQL update
trigger that returns NULL.
Reviewed by Tim Graham.
Refs #16649
Backport of e973ee6a9879969b8ae05bb7ff681172cc5386a5 from master
Conflicts:
django/db/models/options.py
tests/basic/tests.py