system, whereby using a :class:`.TypeDecorator` in conjunction with
variant would fail with an MRO error when a comparison operator was used.
fixes #3102

ProgrammingError, not OperationalError, in modern MySQL-Python versions;
all MySQL error codes that are tested for "is disconnect" are now
checked within OperationalError and ProgrammingError regardless.
fixes #3101

of :ticket:`3060` from verision 0.9.5.  A self-referential relationship
with lazy='dynamic' would raise a TypeError within a flush operation.
fixes #3099

distinguished for when it was actually the value ``False``.
The ``__abstract__`` flag needs to acutally evaluate to a True
value at the level being tested.
fixes #3097

when we do a get; we return the None as always but we leave the dict blank
and the loader callable still in place.  The case for this implicit get on a pending object is not
super common and there really should be no change in state at all when this
operation proceeds.   This change is more dramatic as it reverses
a behavior SQLA has had since the first release.
fixes #3061

fix that is updated more comprehensively in 1.0 via :ticket:`3061`.
The fix in :ticket:`3060` unfortunately produces a new issue whereby
an eager load of a many-to-one attribute can produce an event
that is interpreted into an attribute change.

mapper is implicitly combining one of its column-based attributes
with that of the parent, where those columns normally don't necessarily
share the same value.  This is an extension of an existing check that
was added via :ticket:`1892`; however this new check emits only a
warning, instead of an exception, to allow for applications that may
be relying upon the existing behavior.
fixes #3042

when that :class:`.Column` is referred to in an explicit
:class:`.PrimaryKeyConstraint` for that table.  This behavior now
matches that of when the :class:`.Column` itself has the
:paramref:`.Column.primary_key` flag set to ``True``, which is
intended to be an exactly equivalent case.
fixes #3023