Replace state for when initially setting the URL

This saves pushing the state & creating a new history entry

app/assets/javascripts/boards/boards_bundle.js

@@ -70,7 +70,7 @@ $(() => {
         splitPath = [milestoneTitleParam].concat(splitPath);
         Store.filter.path = splitPath.join('&');
 
-        Store.updateFiltersUrl();
+        Store.updateFiltersUrl(true);
       }
 
       gl.boardService = new BoardService(this.endpoint, this.bulkUpdatePath, this.boardId);

app/assets/javascripts/boards/stores/boards_store.js

@@ -124,8 +124,12 @@
         return list[key] === val && byType;
       })[0];
     },
-    updateFiltersUrl () {
+    updateFiltersUrl (replaceState = false) {
+      if (replaceState) {
+        history.replaceState(null, null, `?${this.filter.path}`);
+      } else {
         history.pushState(null, null, `?${this.filter.path}`);
       }
+    }
   };
 })();