.. change::
    :tags: change, sql
    :tickets: 4632

    The "threadlocal" execution strategy, deprecated in 1.3, has been
    removed for 1.4, as well as the concept of "engine strategies" and the
    ``Engine.contextual_connect`` method.  The "strategy='mock'" keyword
    argument is still accepted for now with a deprecation warning; use
    :func:`.create_mock_engine` instead for this use case.

    .. seealso::

        :ref:`change_4393_threadlocal` - from the 1.3 migration notes which
        discusses the rationale for deprecation.