Problem with multiple SUMs

After recent changes I find an error with SUM when summing more than
one column. Here is the test sequence.

DROP TABLE x;
CREATE TABLE x (a int, b int);
INSERT INTO x VALUES (1, 5);
INSERT INTO x VALUES (2, 7);
SELECT * FROM x;
SELECT SUM(a) FROM x;
SELECT SUM(b) FROM x;
SELECT SUM(a), SUM(b) FROM x;

The last three statements give the following expected results when
run on a system compiled Jan 19.

darcy=> SELECT SUM(a) FROM x;
sum
---
3
(1 row)

darcy=> SELECT SUM(b) FROM x;
sum
---
12
(1 row)

darcy=> SELECT SUM(a), SUM(b) FROM x;
sum|sum
---+---
3| 12
(1 row)

On a system compiled Jan 27, I see the following.

darcy=> SELECT SUM(a) FROM x;
sum
---
3
(1 row)

darcy=> SELECT SUM(b) FROM x;
sum
---
12
(1 row)

darcy=> SELECT SUM(a), SUM(b) FROM x;
sum|sum
---+---
12| 12
(1 row)

See how the individual sums are correct but I can no longer get both
sums in one select.

--
D'Arcy J.M. Cain <darcy(at){druid|vex}.net> | Democracy is three wolves
http://www.druid.net/darcy/ | and a sheep voting on
+1 416 424 2871 (DoD#0082) (eNTP) | what's for dinner.