ST_PreserveTopology breaks narrow polygon

[strk]

I've the polygon of a river with a small island that becomes invalid after ST_PreserveTopology is called on it, with a relatively large tolerance.

The invalidity is "Hole lies outside shell", which makes me think such occurrence isn't being checked for preservation.

\cc Martin Davis

I've spotted this with POSTGIS="2.2.0dev r13965" GEOS="3.5.0dev-CAPI-1.9.0 r4059" Waiting for permissions before sharing the input (or I'll cut it in pieces later)

[mdavis]

This is fixed in GEOS by ​https://github.com/libgeos/geos/pull/1012