id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
14974	GeoJSON export: some ways gets exported as polygons	TobWen	TobWen	"Ways with some tags get exported as polygons when exporting to GeoJSON.

Try this fake way:
{{{
#!xml
<?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:

{{{
#!json
        {
            ""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."	defect	closed	normal	17.06	Core geojson	latest	fixed	GeoJSON, polygon