Actually move NullResource back into the method scope, to avoid import ordering problems

src/OFS/Traversable.py

@@ -27,7 +27,6 @@ from Acquisition import aq_inner
 from Acquisition import aq_parent
 from Acquisition.interfaces import IAcquirer
 from OFS.interfaces import ITraversable
-from webdav.NullResource import NullResource
 from zExceptions import NotFound
 from ZPublisher.interfaces import UseTraversalDefault
 from ZODB.POSException import ConflictError
@@ -172,6 +171,8 @@ class Traversable:
         else:
             obj = self
 
+        # import time ordering problem
+        from webdav.NullResource import NullResource
         resource = _marker
         try:
             while path: