Voronoi diagram fails when the points are from the ring of a circle

[ajolma]

I have a set of points from the ring of a circle. If I select all or almost all of them for voronoi diagram computation, it fails with

GEOSVoronoiDiagram: TopologyException: Input geom 1 is invalid: Self-intersection at or near point 360736.47000001703 7127320.700000016 at 360736.47000001703 7127320.700000016

There is a clear boundary where the error happens (I'm using PostGIS), this fails:

SELECT ST_VoronoiPolygons(geom) As geom
FROM (SELECT st_collect(geom) as geom from s where i < 248) As g;

but this does not fail:

SELECT ST_VoronoiPolygons(geom) As geom
FROM (SELECT st_collect(geom) as geom from s where i < 247) As g;

Versions are

POSTGIS="3.0.0dev r17356" [EXTENSION] PGSQL="100" GEOS="3.8.0rc2-CAPI-1.13.1 " PROJ="Rel. 5.2.0, September 15th, 2018" LIBXML="2.9.4" LIBJSON="0.12.1" LIBPROTOBUF="1.2.1"

[robe]

Retargeting in prep for GEOS 3.10.0 release