Fix T70244: FBX bug import when having children rigs of parent one.

Note that such complex rig features remains barely supported anyway,
such complex setup will require some manual editing after import...

io_scene_fbx/__init__.py

@@ -21,7 +21,7 @@
 bl_info = {
     "name": "FBX format",
     "author": "Campbell Barton, Bastien Montagne, Jens Restemeier",
-    "version": (4, 17, 0),
+    "version": (4, 17, 1),
     "blender": (2, 81, 6),
     "location": "File > Import-Export",
     "description": "FBX IO meshes, UV's, vertex colors, materials, textures, cameras, lamps and actions",

io_scene_fbx/import_fbx.py

@@ -1898,7 +1898,11 @@ class FbxImportHelperNode:
 
             meshes = set()
             for child in self.children:
-                child.collect_skeleton_meshes(meshes)
+                # Children meshes may be linked to children armatures, in which case we do not want to link them
+                # to a parent one. See T70244.
+                child.collect_armature_meshes()
+                if not child.meshes:
+                    child.collect_skeleton_meshes(meshes)
             for m in meshes:
                 old_matrix = m.matrix
                 m.matrix = armature_matrix_inv @ m.get_world_matrix()