Export: +Y Up off broken for bones
The model from #1607 is broken when exporting with "+Y Up" off with master. It worked in 3.0.

The first bad commit is 67ec397d. The problem appears to be that the axis_basis_change code here forgets to handle the "+Y Up" off case

https://github.com/KhronosGroup/glTF-Blender-IO/blob/60c634eac89a4cef444cfcd8204bdf797db2f5cb/addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_tree.py#L184-L185

Compare with

https://github.com/KhronosGroup/glTF-Blender-IO/blob/60c634eac89a4cef444cfcd8204bdf797db2f5cb/addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_tree.py#L437-L440
diff --git a/addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_tree.py b/addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_tree.py
index 1f96c11d..1843a517 100644
--- a/addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_tree.py
+++ b/addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_tree.py
@@ -181,8 +181,10 @@ class VExportTree:
                 node.matrix_world @= correction.to_matrix().to_4x4()
         elif node.blender_type == VExportNode.BONE:
             node.matrix_world = self.nodes[node.armature].matrix_world @ blender_bone.matrix
-            axis_basis_change = Matrix(
-                ((1.0, 0.0, 0.0, 0.0), (0.0, 0.0, 1.0, 0.0), (0.0, -1.0, 0.0, 0.0), (0.0, 0.0, 0.0, 1.0)))
+            axis_basis_change = Matrix.Identity(4) 
+            if self.export_settings[gltf2_blender_export_keys.YUP]:
+                axis_basis_change = Matrix(
+                    ((1.0, 0.0, 0.0, 0.0), (0.0, 0.0, 1.0, 0.0), (0.0, -1.0, 0.0, 0.0), (0.0, 0.0, 0.0, 1.0)))
             node.matrix_world = node.matrix_world @ axis_basis_change
 
         # Force empty ?
['addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_tree.py']