.

wcfs/internal/xbtree.py

@@ -366,7 +366,12 @@ def Restructure(ztree, newStructure):
 
             # https://github.com/zopefoundation/BTrees/blob/4.5.0-1-gc8bf24e/BTrees/BTreeTemplate.c#L1087
             if len(node.keyv) == 0:
-                panic("TODO: empty tree + tree with bucket without oid")
+                child = node.children[0]
+                if isinstance(child, Bucket):
+                    if len(child.keyv) == 0:
+                        panic("TODO: empty tree")
+                    if child.Z._p_oid is None:
+                        panic("TODO: tree with bucket without oid")
 
             zstate = ()
             assert len(node.children) == len(node.keyv) + 1