commit e549722a
Author: Tom Lane <tgl@sss.pgh.pa.us>
Date:   Wed Feb 25 03:30:38 2009 +0000

    Get rid of the rather fuzzily defined FlattenedSubLink node type in favor of
    making pull_up_sublinks() construct a full-blown JoinExpr tree representation
    of IN/EXISTS SubLinks that it is able to convert to semi or anti joins.
    This makes pull_up_sublinks() a shade more complex, but the gain in semantic
    clarity is worth it.  I still have more to do in this area to address the
    previously-discussed problems, but this commit in itself fixes at least one
    bug in HEAD, as shown by added regression test case.

Ref [#142356521]
Signed-off-by: NEkta Khanna <ekhanna@pivotal.io>