would be turned into a list of individual characters.  This would
impact among other things using the :meth:`.Query.get` method
on a primary key that's a bytes object.
fixes #3660

(cherry picked from commit 01809bddff5b6e93010eb139aed54526c6e6c058)

the warning here to all safe_reraise() cases in Python 2.
- Revisiting :ticket:`2696`, first released in 1.0.10, which attempts to
work around Python 2's lack of exception context reporting by emitting
a warning for an exception that was interrupted by a second exception
when attempting to roll back the already-failed transaction; this
issue continues to occur for MySQL backends in conjunction with a
savepoint that gets unexpectedly lost, which then causes a
"no such savepoint" error when the rollback is attempted, obscuring
what the original condition was.

The approach has been generalized to the Core "safe
reraise" function which takes place across the ORM and Core in any
place that a transaction is being rolled back in response to an error
which occurred trying to commit, including the context managers
provided by :class:`.Session` and :class:`.Connection`, and taking
place for operations such as a failure on "RELEASE SAVEPOINT".
Previously, the fix was only in place for a specific path within
the ORM flush/commit process; it now takes place for all transational
context managers as well.
fixes #2696

(cherry picked from commit 8a1e619fb20df1be6ad2e0c563e451e17eb17628)

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

(cherry picked from commit d4d9a6524886eb33644e8ce42212267fa569e555)

are now exercised within the normal unit test suite in both Python
2 and Python 3.
- remove the old testdocs.py runner and replace with test/base/test_tutorials.py
- use pytest's unicode fixer so that we can test for unicode strings
in both py2k/3k
- use py3k format overall for prints, exceptions
- add other fixers to guarantee deterministic results
- add skips and ellipses to outputs that aren't worth matching

(cherry picked from commit d533b8e9223b9c938655e5b666fc928e2d996cd3)

The error message changed to:

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

(cherry picked from commit d9178320d6755d893638646503ed538b11b6536a)

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.

pep-249 exception names linked to exception classes of an entirely
different name, preventing SQLAlchemy's own exception wrapping from
wrapping the error appropriately.
The SQLAlchemy dialect in use needs to implement a new
accessor :attr:`.DefaultDialect.dbapi_exception_translation_map`
to support this feature; this is implemented now for the py-postgresql
dialect.
fixes #3421