Log Message:
-----------
Make constant-folding produce sane output for COALESCE(NULL,NULL),
that is a plain NULL and not a COALESCE with no inputs. Fixes crash
reported by Michael Williamson.
Modified Files:
--------------
pgsql/src/backend/optimizer/util:
clauses.c (r1.193 -> r1.194)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/util/clauses.c.diff?r1=1.193&r2=1.194)