Store.get() on invalidated objects should retrieve all fields rather than just checking the object is alive

[James Henstridge]

If we have an invalidated Python object for a given row in a table, Store.get() will return that object after calling Store._validate_alive(), which results in a query. None of the fields will be filled out at this point, so another query will be issued as soon as we try to use the object.

If we are going to suffer a database round trip anyway it would seem sensible to fill out the entire object in this case, since it is likely that the caller will want to use the object it has just requested.

[James Henstridge (jamesh)]

Attached is a test program. In the first transaction, retrieving the object and accessing an attribute results in one query:

    SELECT foo.id, foo.name FROM foo WHERE foo.id = 1 LIMIT 1

The second transaction, which performs identical actions issues two queries:

    SELECT 1 FROM foo WHERE foo.id = 1
    SELECT foo.name FROM foo WHERE foo.id = 1

[James Henstridge (jamesh)]

Fix merged to trunk in r385.