ImportMesh not unblocking when complete

[JCPalmer]

In my testing of FileLoader logging, I wanted to make sure the messages worked for ImportMesh too.  They did, but scene.executeWhenReady() is never run.

My test had 2 appends & an executeWhenReady block which worked as desired:

BABYLON.SceneLoader.loggingLevel = BABYLON.SceneLoader.DETAILED_LOGGING;
BABYLON.SceneLoader.Append(url, "armature-no-anim.babylon", scene);
BABYLON.SceneLoader.Append(url, "skeleton_library.babylon", scene);
scene.executeWhenReady(function () {
   console.log("i am ready");
}

I substituted an ImportMesh(null, for the first Append(.  The logging worked, but never got to the "i am ready" message.  I see the 2 scene._removePendingData calls in ImportMesh.  Maybe a finally block with just one call would be better.