Part of the old-style multipolygon handling is the "inserted way" cache, that stores which (outer or inner) way of a relation does not need to be imported anymore, because it shares the same tags as the multipolygon relation.
For example: A forest multipolygon relation with a hole where the outer way is also tagged as forest. Only the relation should be imported and not the outer way (as this polygon will cover the hole in the multipolygon).
While old-style multipolygons are removed, tagged outer ways are still present. See: osmlab/fixing-polygons-in-osm/issues/36
The "inserted ways" handling can be removed when this issue is fixed in the OSM data, or when openstreetmap-carto deploys 4.0 where this handling is dropped.
olt
commented
5 years ago
Part of the old-style multipolygon handling is the "inserted way" cache, that stores which (outer or inner) way of a relation does not need to be imported anymore, because it shares the same tags as the multipolygon relation.
For example: A forest multipolygon relation with a hole where the outer way is also tagged as forest. Only the relation should be imported and not the outer way (as this polygon will cover the hole in the multipolygon).
While old-style multipolygons are removed, tagged outer ways are still present. See: osmlab/fixing-polygons-in-osm/issues/36 The "inserted ways" handling can be removed when this issue is fixed in the OSM data, or when openstreetmap-carto deploys 4.0 where this handling is dropped.