[PostGIS] #5825: ST_ConcaveHull gives unexpected result with MultiPolygon

[PostGIS]

#5825: ST_ConcaveHull gives unexpected result with MultiPolygon
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  Reporter:  nbvfgh     |      Owner:  strk
      Type:  defect     |     Status:  new
  Priority:  critical   |  Milestone:  PostGIS 3.5.2
 Component:  liblwgeom  |    Version:  3.5.x
Resolution:             |   Keywords:
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Comment (by nbvfgh):

 To add, when converted into a set of points, the result is as expected.
 {{{
 WITH mp AS(
         SELECT ST_GeomFromText('MULTIPOLYGON (((0 0, 1 0, 2 1, 1 1, 0
 0),(0 0, 1 1, 2 1, 0 0)),
                                       ((8 2, 8 4, 10 4, 10 2, 8 2)),
                                       ((4 9, 5 9, 5 8, 4 8, 4 9)))'
         ) geom
 )
 SELECT ST_AsText(ST_ConcaveHull(ST_Points(mp.geom), 0,false)),
            ST_ConcaveHull(ST_Points(mp.geom), 0,false) from mp;

 -- result: { POLYGON((4 8,4 9,5 9,5 8,10 4,10 2,8 2,1 0,0 0,1 1,2 1,8 4,4
 8)) }
 }}}
 [[Image(https://github.com/user-attachments/assets/90afce55-af06-4c2c-
 93c5-439a9224f00f)]]
-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/5825#comment:1>
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