GeoJSON export: some ways gets exported as polygons

[TobWen]

Ways with some tags get exported as polygons when exporting to GeoJSON.

Try this fake way:

<?xml version='1.0' encoding='UTF-8'?>
<osm version='0.6' generator='JOSM'>
  <node id='-76119' lat='51.5099031' lon='6.8806761'>
    <tag k='highway' v='footway' />
  </node>
  <node id='-76121' lat='51.5097885' lon='6.9040016'>
    <tag k='highway' v='footway' />
  </node>
  <way id='-76135' action='modify'>
    <nd ref='-76119' />
    <nd ref='-76121' />
    <tag k='highway' v='footway' />
    <tag k='man_made' v='surveillance' />
  </way>
</osm>

When exporting it to GeoJSON, it gets:

        {
            "type":"Feature",
            "properties":{
                "highway":"footway",
                "man_made":"surveillance"
            },
            "geometry":{
                "type":"Polygon",
                "coordinates":[
                    [
                        [
                            6.88067610000,
                            51.50990310000
                        ],
                        [
                            6.90400160000,
                            51.50978850000
                        ]
                    ]
                ]
            }
        }

Changing a non-closed ways into an area produces lots of trouble of course.

Furthermore, according to the wiki, man_made = surveillance is mainly used on points, but can also be used on ways and polygons.