extra lazy joined test

Hi,

This is just a bug report, not an actual PR, you don't have to merge.

When you have a JOINED inheritance, and you have another class, which is related to the parent class of the inheritance, and you only have an association for one of the child classes, EXTRA_LAZY fetch mode creates a fatal error, because it is not joining the parent table to the count query.

There are many ways around this fortunately, but I thought I should report it anyway.