debug logging message would not emit if the logging were set up using
``logging.setLevel()``, rather than using the ``echo_pool`` flag.
Tests to assert this logging have been added.  This is a
regression that was introduced in 0.9.0.
fixes #3168

for an INSERT or UPDATE are now sorted when they contribute towards
the "compiled cache" cache key.   These keys were previously not
deterministically ordered, meaning the same statement could be
cached multiple times on equivalent keys, costing both in terms of
memory as well as performance.
fixes #3165

In test/engine/test_transaction/test_two_phase_recover(), a COMMIT
PREPARED is issued while in a transaction. This causes an error, and
a prepared transaction is left hanging around which causes
the subsequent test to hang. I've altered the test to execute the
offending query with autocommit=true, then when it gets to the COMMIT
PRPARED it can go ahead.

There's another complication for pg8000 because its tpc_recover() method
started a transaction if one wasn't already in progress. I've decided
that this is incorrect behaviour and so from pg8000-1.9.13 this method
never starts or stops a transaction.