KNN GiST detects which type it should return by returning type of ordering operator.
But it appears that type of sk_func is detected after it was replaced with distance function. That is wrong: distance function should always return float8.
I think it is just a typo.
Should be backpatched to 9.5.
------ Alexander Korotkov Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
KNN GiST detects which type it should return by returning type of ordering operator.
But it appears that type of sk_func is detected after it was replaced with distance function. That is wrong: distance function should always return float8.