Commit 8526bcb2 fixed bugs related
to both Sort and Hash, but only added a test case for Sort.  This
adds a test case for Hash to match.

Thomas Munro

Discussion: http://postgr.es/m/CAEepm=2-LRnfwUBZDqQt+XAcd0af_ykNyyVvP3h1uB1AQ=e-eA@mail.gmail.com