emergency: rebase reversed route distances

vendor/clouds3d.js

@@ -3620,7 +3620,9 @@ function selectEmergencyRoutes() {
         used[usedKey] = true;
         var route = emergencyChainAt(cand.net, cand.ci);
         if (cand.reverse) route.reverse();
-        var len = route.length ? route[route.length - 1].d - route[0].d : 0;
+        var base = route.length ? route[0].d : 0;
+        for (var rp = 0; rp < route.length; rp++) route[rp].d -= base;
+        var len = route.length ? route[route.length - 1].d : 0;
         if (len <= 0) continue;
         emergencyRoutes.push({ pts: route, len: len, lenKm: len * KM_PER_TILE, nearKm: cand.near * KM_PER_TILE });
     }