Buffer op throws exception for multipolygon

[mwtoews]

This issue was reported here: shapely/shapely#2174

It involves valid polygons (p1 in blue and p2 in red) and their valid multipolygon (mp).

$ cat > p1.wkb
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
$ cat > p2.wkb
01030000000100000007000000B7EEE6A92235E5400ABFD4CFE44DE9C0E4DA503103BEE440202922C3DE18EBC0D8800871B4BDE4402E8ECACD0C1AEBC06C09F9A006BEE440172CD585D118EBC0A2D3F3EE47BEE440E962D3CABD17EBC0193735D04DBEE440A06B5F40BF17EBC0B7EEE6A92235E5400ABFD4CFE44DE9C0
$ cat > mp.wkb
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

Firstly, the negative buffer Op works on the individual polygons:

$ ./geosop -a p1.wkb buffer N-1
POLYGON ((-1664 ...
$ ./geosop -a p2.wkb buffer N-1
POLYGON EMPTY

But crashes with the multipolygon:

$ ./geosop -a mp.wkb buffer N-1
Run-time exception: TopologyException: unable to assign hole to a shell

This is a regression, as GEOS 3.11.0 handles mp as expected. It is broken from 3.11.1 thru to 3.13.0 and main branch.

Doing a few bisections, the break is from 6297b6a via #707

I should also briefly note that with JTS, this issue sort-of works. It handles each p1 and p2 as expected, but the mp version appears to snap-round the coordinates to the nearest 10, indicating this a separate issue.