Skip PK returned as None for RETURNING, server side default

Fixed regression where the ORM exception that is to be raised when an
INSERT silently fails to actually insert a row (such as from a trigger)
would not be reached, due to a runtime exception raised ahead of time due
to the missing primary key value, thus raising an uninformative exception
rather than the correct one. For 1.4 and above, a new ``FlushError`` is
added for this case that's raised earlier than the previous "null identity"
exception was for 1.3, as a situation where the number of rows actually
INSERTed does not match what was expected is a more critical situation in
1.4 as it prevents batching of multiple objects from working correctly.
This is separate from the case where a newly fetched primary key is
fetched as NULL, which continues to raise the existing "null identity"
exception.

Fixes: #7594
Change-Id: Ie8e181e3472f09f389cca757c5e58e61b15c7d79

0 files changed, 0 insertions, 0 deletions