Use admin_center for reverse geocoding

[StephaneP]

If I reverse geocode an isolated dwelling, it returns correctly the city : ​http://nominatim.openstreetmap.org/reverse?format=xml&osm_type=N&osm_id=2514066146&zoom=18&addressdetails=1 The city is "Saint-Hilaire-de-Clisson"

But it's not the case if I reverse geocode a hamlet : ​http://nominatim.openstreetmap.org/reverse?format=xml&osm_type=N&osm_id=1281300035&zoom=18&addressdetails=1

I know that hamlets and villages are on the same level for nominatim and it explains why it doesn't return "Saint-hilaire-de-clisson". But in France there are a lot of hamlet with the same name inside an admin_level=7 boundary. "Beaulieu", "Bellevue", "Bel Air" are some examples. If you don't know in which city/village this hamlet is, you're lost : Search for "bel-air" on admin_level=7 ​http://nominatim.openstreetmap.org/search.php?q=bel+air+in+nantes&viewbox=-3.73%2C47.85%2C0.96%2C45.92

I don't ask for moving hamlet to another level, but to use the admin_center of the admin_level 8 boundary.