repaired to work more usefully with tables that have Python-
side default values and/or functions, as well as server-side
defaults. The feature will now work with a dialect that uses
"positional" parameters; a Python callable will also be
invoked individually for each row just as is the case with an
"executemany" style invocation; a server- side default column
will no longer implicitly receive the value explicitly
specified for the first row, instead refusing to invoke
without an explicit value. fixes #3288

defaults if otherwise unspecified; the limitation where non-
server column defaults aren't included in an INSERT FROM
SELECT is now lifted and these expressions are rendered as
constants into the SELECT statement.

CC goes from F to D