Fix mesh double loading (#6034)

* Fix mesh double loading

* restore

* better fix

* better fix

* restore downloader

* changelog

Author: Benjamin Délèze

docs/reference/changelog-r2023.md

@@ -12,7 +12,7 @@ Released on ??
     - Improved default selected tab in Field Editor when nodes are selected ([#5726](https://github.com/cyberbotics/webots/pull/5726)).
     - Change the Windows version of SUMO to 1.13 to match the one used on Linux and MacOS and avoid a potiental Log4J vulnerability ([#6010](https://github.com/cyberbotics/webots/pull/6010)).
   - Bug Fixes
-    - Fixed the clean-up of the motion API which was firing warnings in Python ([#6029](https://github.com/cyberbotics/webots/pull/6029)). 
+    - Fixed the clean-up of the motion API which was firing warnings in Python ([#6029](https://github.com/cyberbotics/webots/pull/6029)).
     - Fixed the behavior of the [Connector](connector.md) after a reset to return to the controller the correct status ([#5889](https://github.com/cyberbotics/webots/pull/5889))
     - Fixed redirection of stdout/stderr for Python controllers on Windows ([#5807](https://github.com/cyberbotics/webots/pull/5807)).
     - Fixed crash in Python API when a robot controller was using several cameras with different resolutions ([#5705](https://github.com/cyberbotics/webots/pull/5705)).
@@ -52,6 +52,7 @@ Released on ??
     - Fixed physics state updates of [Solid](solid.md) nodes added to a descendant [`Joint.endPoint`](joint.md) during simulation ([#5961](https://github.com/cyberbotics/webots/pull/5961)).
     - Fixed unwanted altitude change when reaching a target waypoint in `mavic2pro_patrol.c` ([#5981](https://github.com/cyberbotics/webots/pull/5981)).
     - Fixed the extern controller connection to a target Webots instance when a snap one is running ([#6002](https://github.com/cyberbotics/webots/pull/6002)).
+    - Fixed the double downloading of meshes ([#6034](https://github.com/cyberbotics/webots/pull/6034)).
 
 ## Webots R2023a
 Released on November 29th, 2022.

src/webots/nodes/WbMesh.cpp

@@ -336,7 +336,9 @@ void WbMesh::updateUrl() {
           mDownloader = NULL;
         }
 
-        downloadAssets();  // URL was changed from the scene tree or supervisor
+        if (!mDownloader || mDownloader->url().toString() != mUrl->item(0))
+          downloadAssets();  // URL was changed from the scene tree or supervisor
+
         return;
       }
     }