- Related to :ticket:`3060`, an adjustment has been made to the unit
    of work such that loading for related many-to-one objects is slightly
    more aggressive, in the case of a graph of self-referential objects
    that are to be deleted; the load of related objects is to help
    determine the correct order for deletion if passive_deletes is
    not set.
    - revert the changes to test_delete_unloaded_m2o, these deletes do in fact
    need to occur in the order of the two child objects first.

merged from master