Remove boundries when downgrading from polygon to line

Fixes #135.

sql/functions.sql

@@ -2144,6 +2144,12 @@ BEGIN
           NEW.name := hstore('ref', NEW.address->'postcode');
       END IF;
 
+      IF NEW.class in ('boundary')
+         AND ST_GeometryType(NEW.geometry) not in ('ST_Polygon','ST_MultiPolygon') THEN
+          DELETE FROM placex where place_id = existingplacex.place_id;
+          RETURN NULL;
+      END IF;
+
       update placex set 
         name = NEW.name,
         address = NEW.address,

test/bdd/db/update/simple.feature

@@ -69,3 +69,19 @@ Feature: Update of simple objects
         Then placex contains
           | object | class | type |
           | N3     | place | house |
+
+    Scenario: remove boundary when changing from polygon to way
+        Given the grid
+          | 1 | 2 |
+          | 3 | 4 |
+        And the places
+          | osm | class    | type           | name | admin | geometry        |
+          | W1  | boundary | administrative | Haha | 5     | (1, 2, 4, 3, 1) |
+        When importing
+        Then placex contains
+          | object |
+          | W1 |
+        When updating places
+          | osm | class    | type           | name | admin | geometry   |
+          | W1  | boundary | administrative | Haha | 5     | 1, 2, 4, 3 |
+        Then placex has no entry for W1