that intercepts a query and adds entity-oriented criteria

limit/offset criteria that forces a subquery b. the relationship
uses "secondary" c. the primaryjoin of the relationship refers to
a column that is either not part of the primary key, or is a PK
col in a joined-inheritance subclass table that is under a different
attribute name than the parent table's primary key column d. the
query defers the columns that are present in the primaryjoin, typically
via not being included in load_only(); the necessary column(s) would
not be present in the subquery and produce invalid SQL.
fixes #3592

scope of a :meth:`.Session.flush` operation that's raising an
exception, as has been observed in some MySQL SAVEPOINT cases, prevents
the original  database exception from being observed when it was
emitted during  flush, but only on Py2K because Py2K does not support
exception  chaining; on Py3K the originating exception is chained.  As
a workaround, a warning is emitted in this specific case showing at
least the string message of the original database error before we
proceed to raise  the rollback-originating exception.
fixes #2696

relationship flag; this flag *does* have an effect when the baked
lazy loader plugin has been invoked.  clarify the intent of this
flag as an "opt out" but only has an effect when the baked system
is loaded anyway.  fixes #3572

added onto the end of a query in some inappropriate situations, such
as when querying from an exists() of a single-inheritance subclass.

fixes #3582

(cherry picked from commit 3ffe8569fbaa72c2d844604b600c4661097339eb)

as versioning isn't needed, fixes test_unitofworkv2->test_update_multi_missing_broken_multi_rowcount

for UPDATE statements in the ORM (e.g. :ref:`feature_updatemany`)
would break on Postgresql and other RETURNING backends
when using server-side version generation
schemes, as the server side value is retrieved via RETURNING which
is not supported with executemany.
fixes #3556