Unwanted way in planet_osm_polygon with test .osm

I have run the following command lines:
```
./osm2pgsql --slim -Sdefault.style -dosm2pgsql-test -C100 -x -k --hstore-match-only tests/liechtenstein-2013-08-03.osm.pbf
osmconvert tests/liechtenstein-2013-08-03.osm.pbf --out-osm > tests/liechtenstein-2013-08-03.osm
./osm2pgsql --slim -Sdefault.style -dosm2pgsql-test -C100 -x -k --hstore-match-only tests/liechtenstein-2013-08-03.osm
```
In the first command line, way 25453075 is missing from planet_osm_polygon, but not on the second command line. This is a landuse=forest way, without any special attribute.

After some investigation, pgsql_add_way() is correctly having filter=0 and polygon=1 in both cases, and psql_out_way() is called with this way id from pgsql_out_stop() only in the .osm case. I'm not sure yet where the difference is coming from.