[1.7.x] Prevented a crash in the cursor wrappers on Oracle.

    def __exit__(self, type, value, traceback):

        # Ticket #17671 - Close instead of passing thru to avoid backend

        # specific behavior.

        # specific behavior. Catch errors liberally because errors in cleanup

        # code aren't useful.

        try:

            self.close()

        except self.db.Database.Error:

            pass

    # The following methods cannot be implemented in __getattr__, because the

    # code must run when the method is invoked, not just when it is accessed.