ST_StraightSkeleton returns degenerate line segments

[robe2]

PostGIS related ticket at: https://trac.osgeo.org/postgis/ticket/3835
returns some lines that are 0 length.

`
WITH bt(box) AS (
SELECT st_makebox2d(st_point(1296000,202400),st_point(1297000,212400))
)
SELECT d.path[1], St_astext(d.geom) , ST_Length(d.geom)
FROM bt, st_dump(
st_straightskeleton(st_difference(st_buffer(box,2000,2),box))
) as d
WHERE st_startpoint(d.geom) = st_endpoint(d.geom);

`

Outputs
`

path | st_astext | st_length
------+-------------------------------------------------------------------------------+-----------
17 | LINESTRING(1295198.91236738 201598.91236738,1295198.91236738 201598.91236738) | 0
20 | LINESTRING(1295198.91236738 213201.08763262,1295198.91236738 213201.08763262) | 0
22 | LINESTRING(1297801.08763262 201598.91236738,1297801.08763262 201598.91236738) | 0
23 | LINESTRING(1297801.08763262 213201.08763262,1297801.08763262 213201.08763262) | 0
(4 rows)

`

This is testing with SFCGAL master as of aa5c4d7

[lbartoletti]

Confirmed with SFCGAL 1.3.7 / Postgis 3.0.1 and CGAL 5.0