thrown off during a collection replace event, if the
reorder_on_append flag were set to True.  The fix ensures that the
ordering list only impacts the list that is explicitly associated
with the object.
fixes #3191

to get all flake8 passing

Found using: https://github.com/intgr/topy

it for DELETE would fail to target the correct row for DELETE.
Then to compound matters, basic "number of rows matched" checks were
not being performed.  Both issues are fixed, however note that the
"rows matched" check requires so-called "sane multi-row count"
functionality; the DBAPI's executemany() method must count up the
rows matched by individual statements and SQLAlchemy's dialect must
mark this feature as supported, currently applies to some mysql dialects,
psycopg2, sqlite only. fixes #3006
- Enabled "sane multi-row count" checking for the psycopg2 DBAPI, as
this seems to be supported as of psycopg2 2.0.9.