- The :paramref:`.Column.nullable` flag is implicitly set to ``False``
when that :class:`.Column` is referred to in an explicit
:class:`.PrimaryKeyConstraint` for that table.  This behavior now
matches that of when the :class:`.Column` itself has the
:paramref:`.Column.primary_key` flag set to ``True``, which is
intended to be an exactly equivalent case.
fixes #3023
add missing version markers
additional version notes