BUG #5889: "Intersects" for polygons broken

The following bug has been logged online:

Bug reference: 5889
Logged by: Konrad Garus
Email address: konrad(dot)garus(at)gmail(dot)com
PostgreSQL version: 8.4
Operating system: Linux
Description: "Intersects" for polygons broken
Details:

&& operator seems to be broken for polygons whose bounding boxes intersect:

select polygon'((0,0), (1,2), (0,2))' && polygon'((0.5, 0), (1,0), (1,1))';
?column?
----------
t
(1 row)

It reportedly is different in 9.0
(http://stackoverflow.com/q/5015233/277683)

Docs could do better job explaining what types each of the geometry operator
supports, and whether intersecting polygons support nonconvex polygons as
well, or only uses bounding box as criteria.