to use a named def instead of a lambda.  this so that TypeError on wrong
arguments are more legible.  [ticket:2884]

``__repr__()``, particularly with regards to the MySQL integer/numeric/
character types which feature a wide variety of keyword arguments.
The ``__repr__()`` is important for use with Alembic autogenerate
for when Python code is rendered in a migration script.
[ticket:2893]

connection to be available, such that for a connection pool
with no timeout specified, it will every half a second break out of
the wait to check for the so-called "abort" flag, which allows the
waiter to break out in case the whole connection pool was dumped;
normally the waiter should break out due to a notify_all() but it's
possible this notify_all() is missed in very slim cases.
This is an extension of logic first introduced in 0.8.0, and the
issue has only been observed occasionally in stress tests.

   "@", or "/" must be encoded." - so re-apply encoding to both password
and username, don't encode spaces as plus signs, don't encode any chars
outside of :, @, / on stringification - but we still parse for any
%XX character (is that right?)

- fix and test weakref cleanout for WeakSequence, [ticket:2794]

by the ORM to iterate mapper hierarchies; under the Jython interpreter
this implementation wasn't ordered, even though cPython and Pypy
maintained ordering.  Also in 0.8.3.
[ticket:2794]

courtesy Hajime Nakagami.