Negative LIMIT and OFFSET?

I'm fairly surprised these queries work. Is there some reason why we
support this? April Fools Day? Jules Verne? I'm all for fast queries,
but zero seems like the lowest value we should support...

postgres=# select * from accounts limit -9;aid | bid | abalance | filler 
-----+-----+----------+--------
(0 rows)

Time: 0.330 ms
postgres=# select * from accounts limit -9 offset 45;aid | bid | abalance | filler 
-----+-----+----------+--------
(0 rows)

Time: 0.268 ms
postgres=# select * from accounts limit -9 offset -100000;aid | bid | abalance | filler 
-----+-----+----------+--------
(0 rows)

Time: 0.287 ms

postgres=# select * from accounts limit 0 offset -100000;aid | bid | abalance | filler 
-----+-----+----------+--------
(0 rows)

Time: 0.289 ms

--  Simon Riggs 2ndQuadrant  http://www.2ndQuadrant.com