the exception to itself as the "cause"; while the Python 3 interpreter
is OK with this, it could cause endless loops in iPython.
fixes #3625
- add tests for reraise, raise_from_cause
- raise_from_cause is the same on py2k/3k, use just one function

The error message changed to:

`'<' not supported between instances of 'foo' and 'bar'`

function; the caller still passes in the "wrapper"
- move tests for wrap_callable() to be generic util tests
- changelog for pullreq github:204

didn't implement ``__slots__``, and therefore meant all subclasses
of that class didn't either, negating the rationale for ``__slots__``
to be in use.  Didn't cause any issue except on IronPython
which apparently does not implement ``__slots__`` behavior compatibly
with cPython.
Fixes #3494

that a Python descriptor is no longer used; repairs inspectability
of these methods including support for Sphinx documentation.

improved in conjunction with loader directives such as
:func:`.joinedload` and :func:`.contains_eager` such that if
two :meth:`.PropComparator.of_type` modifiers of the same
base type/path are encountered, they will be joined together
into a single "polymorphic" entity, rather than replacing
the entity of type A with the one of type B.  E.g.
a joinedload of ``A.b.of_type(BSub1)->BSub1.c`` combined with
joinedload of ``A.b.of_type(BSub2)->BSub2.c`` will create a
single joinedload of ``A.b.of_type((BSub1, BSub2)) -> BSub1.c, BSub2.c``,
without the need for the ``with_polymorphic`` to be explicit
in the query.
fixes #3256

ORM functions that are derived as "public factory" symbols, which
should assist with documentation tools being able to report on the
target module.
fixes #3218

:class:`.Query` object offers dramatic speed improvements when
fetching large numbers of column-oriented rows.
fixes #3176

should be taken