Thread: pgsql: Put back copyObject() call I removed in a fit of brain fade.

Log Message:
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Put back copyObject() call I removed in a fit of brain fade.  This one
is still needed despite cleanups in setrefs.c, because the point is to
let the inserted Result node compute a different tlist than its input
node does.  Per example from Jeremy Drake.

Modified Files:
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    pgsql/src/backend/optimizer/plan:
        createplan.c (r1.226 -> r1.227)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/createplan.c.diff?r1=1.226&r2=1.227)