Merge pull request #8708 from k-yle/keep-oldest-feature-in-merge

keep the oldest Way when merging

modules/actions/join.js

@@ -27,7 +27,6 @@ export function actionJoin(ids) {
 
     var action = function(graph) {
         var ways = ids.map(graph.entity, graph);
-        var survivorID = ways[0].id;
 
         // if any of the ways are sided (e.g. coastline, cliff, kerb)
         // sort them first so they establish the overall order - #6033
@@ -40,12 +39,15 @@ export function actionJoin(ids) {
         });
 
         // Prefer to keep an existing way.
-        for (var i = 0; i < ways.length; i++) {
-            if (!ways[i].isNew()) {
-                survivorID = ways[i].id;
-                break;
-            }
-        }
+        // if there are mulitple existing ways, keep the oldest one
+        // the oldest way is determined by the ID of the way
+        const survivorID = (
+            ways
+                .filter((way) => !way.isNew())
+                .sort((a, b) => +a.osmId() - +b.osmId())[0] || ways[0]
+        ).id;
+
+
 
         var sequences = osmJoinWays(ways, graph);
         var joined = sequences[0];