scope of a :meth:`.Session.flush` operation that's raising an
exception, as has been observed in some MySQL SAVEPOINT cases, prevents
the original  database exception from being observed when it was
emitted during  flush, but only on Py2K because Py2K does not support
exception  chaining; on Py3K the originating exception is chained.  As
a workaround, a warning is emitted in this specific case showing at
least the string message of the original database error before we
proceed to raise  the rollback-originating exception.
fixes #2696

un-adjusted internal symbol names for "anonymous" labels, which
are the "foo_1" types of labels we see generated for SQL functions
without labels and similar.  This was a side effect of the
performance enhancements implemented as part of references #918.
fixes #3483

- fix TablesTest to use the bind that we've returned from setup_bind()
to emit DELETE statements

asserting.

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

use events that are local to the engine and to the run and are removed afterwards.