Removed versionadded and versionchanged for version prior to 1.2 since they
are no longer useful.

Change-Id: I5c53d1188bc5fec3ab4be39ef761650ed8fa6d3e

Change-Id: I625af65b3fb1815b1af17dc2ef47dd697fdc3fb1

command run is "pyupgrade --py37-plus --keep-runtime-typing --keep-percent-format <files...>"
pyupgrade will change assert_ to assertTrue. That was reverted since assertTrue does not
exists in sqlalchemy fixtures

Change-Id: Ie1ed2675c7b11d893d78e028aad0d1576baebb55

Added new parameter :paramref:`.PoolEvents.reset.reset_state` parameter to
the :meth:`.PoolEvents.reset` event, with deprecation logic in place that
will continue to accept event hooks using the previous set of arguments.
This indicates various state information about how the reset is taking
place and is used to allow custom reset schemes to take place with full
context given.

Within this change a fix that's also backported to 1.4 is included which
re-enables the :meth:`.PoolEvents.reset` event to continue to take place
under all circumstances, including when :class:`.Connection` has already
"reset" the connection.

The two changes together allow custom reset schemes to be implemented using
the :meth:`.PoolEvents.reset` event, instead of the
:meth:`.PoolEvents.checkin` event (which continues to function as it always
has).

Change-Id: Ie17c4f55d02beb6f570b9de6b3044baffa7d6df6
Fixes: #8717

Fixed event listening issue where event listeners added to a superclass
would be lost if a subclass were created which then had its own listeners
associated. The practical example is that of the :class:`.sessionmaker`
class created after events have been associated with the
:class:`_orm.Session` class.

Fixes: #8467
Change-Id: I9bdba8769147e30110a09900d4a577e833ac3af9

The :meth:`.DialectEvents.handle_error` event is now moved to the
:class:`.DialectEvents` suite from the :class:`.EngineEvents` suite, and
now participates in the connection pool "pre ping" event for those dialects
that make use of disconnect codes in order to detect if the database is
live. This allows end-user code to alter the state of "pre ping". Note that
this does not include dialects which contain a native "ping" method such as
that of psycopg2 or most MySQL dialects.

Fixes: #5648
Change-Id: I353d84a4f66f309d2467b7e67621db6b8c70411e

I've turned "remove unused imports" back on so this
affects some not-used imports in TYPE_CHECKING blocks

Change-Id: I8b64ff4ec63f4cee01c2bf41399b691e1c3fb04a

also implements __slots__ for QueryableAttribute,
InstrumentedAttribute, Relationship.Comparator.

Change-Id: I47e823160706fc35a616f1179a06c7864089e5b5

in this patch the asyncio/events.py module, which
existed only to raise errors when trying to attach event
listeners, is removed, as we were already coding an asyncio-specific
workaround in upstream Pool / Session to raise this error,
just moved the error out to the target and did the same thing
for Engine.

We also add an async_sessionmaker class.  The initial rationale
here is because sessionmaker() is hardcoded to Session subclasses,
and there's not a way to get the use case of
sessionmaker(class_=AsyncSession) to type correctly without changing
the sessionmaker() symbol itself to be a function and not a class,
which gets too complicated for what this is. Additionally,
_SessionClassMethods has only three methods on it, one of which
is not usable with asyncio (close_all()), the others
not generally used from the session class.

Change-Id: I064a5fa5d91cc8d5bbe9597437536e37b4e801fe