lseg ?# (intersects) incorrect for lsegs whose intersection is another lseg - Mailing list pgsql-bugs

Using PostgreSQL 8.2.3, on linux (FC3):

test=> select lseg'((0,0),(1,0))' ?# lseg'((0,0),(1,0))';
-[ RECORD 1 ]
?column? | f

while

avail=> select lseg'((0,0),(1,0))' ?# lseg'((0,0),(1,1))';
-[ RECORD 1 ]
?column? | t

Looking over the geometric operations source it appears that the
intersect operation applied to line segments will only work if they
intersect at a single point.