- The behavior of =/!= when comparing a scalar select

  - The behavior of =/!= when comparing a scalar select
    to a value will no longer produce IN/NOT IN as of 0.8;
    this behavior is a little too heavy handed (use in_() if
    you want to emit IN) and now emits a deprecation warning.
    To get the 0.8 behavior immediately and remove the warning,
    a compiler recipe is given at
    http://www.sqlalchemy.org/docs/07/dialects/mssql.html#scalar-select-comparisons
    to override the behavior of visit_binary().
    [ticket:2277]