Migrate existing convertibles to generic foldables

data/json/vehicles/bikes.json

@@ -46,6 +46,18 @@
       { "x": -1, "y": 0, "parts": [ "small_storage_battery", "engine_electric_tiny" ] }
     ]
   },
+  {
+    "id": "bicycle_folding",
+    "type": "vehicle",
+    "name": "Folding Bicycle",
+    "blueprint": [ "o#o" ],
+    "parts": [
+      { "x": 0, "y": 0, "parts": [ "folding_frame", "saddle_pedal", "horn_bicycle", "foot_pedals" ] },
+      { "x": 1, "y": 0, "parts": [ "folding_frame", "wheel_mount_light_steerable", "wheel_bicycle" ] },
+      { "x": -1, "y": 0, "parts": [ "folding_frame", "wheel_mount_light" ] },
+      { "x": -1, "y": 0, "parts": [ "wheel_bicycle_rear", "basketsm_bike_rear" ] }
+    ]
+  },
   {
     "id": "motorcycle_cross",
     "type": "vehicle",

src/savegame_json.cpp

@@ -3476,13 +3476,34 @@ void vehicle::deserialize( const JsonObject &data )
         }
     }
 
-    refresh();
-
     data.read( "tags", tags );
     data.read( "fuel_remainder", fuel_remainder );
     data.read( "fuel_used_last_turn", fuel_used_last_turn );
     data.read( "labels", labels );
 
+    // TODO: Remove after 0.G
+    // migrate old "convertible" vehicles to new generic "folding" ones
+    if( has_tag( "convertible" ) ) {
+        // remove tags starting from "convertible"
+        for( auto it = tags.begin(); it != tags.end(); ) {
+            if( it->rfind( "convertible", 0 ) == 0 ) {
+                it = tags.erase( it );
+            } else {
+                ++it;
+            }
+        }
+
+        // only convertible bicycles need to have parts replaced with folding ones, other
+        // in-tree "convertibles" (wheelchair, inflatable boat) can just have their tags
+        // removed as their parts are foldable already
+        if( type == vproto_id( "bicycle" ) ) {
+            type = vproto_id( "bicycle_folding" );
+            parts = type.obj().blueprint->parts;
+        }
+    }
+
+    refresh();
+
     point p;
     zone_data zd;
     for( JsonObject sdata : data.get_array( "zones" ) ) {