- Added support for the not-quite-yet-documented ``insert=True``
flag for :func:`.event.listen` to work with mapper / instance events.
typo
- Improved an error message which would occur if a query() were made
against a non-selectable, such as a :func:`.literal_column`, and then
an attempt was made to use :meth:`.Query.join` such that the "left"
side would be determined as ``None`` and then fail.  This condition
is now detected explicitly.