Use `in` operator instead of deprecated `has_key`.

doc/CHANGES.rst

@@ -8,6 +8,10 @@ http://docs.zope.org/zope2/releases/.
 2.13.12 (unreleased)
 --------------------
 
+- Use ``in`` operator instead of deprecated ``has_key`` method (which
+  is not implemented by ``OFS.ObjectManager``). This fixes an issue
+  with WebDAV requests for skin objects.
+
 - Updated distributions:
 
   - Products.ZCatalog = 2.13.22

src/ZPublisher/BaseRequest.py

@@ -540,9 +540,9 @@ class BaseRequest:
         if (no_acquire_flag and
             hasattr(parents[1], 'aq_base') and
             not hasattr(parents[1],'__bobo_traverse__')):
-            if not (hasattr(parents[1].aq_base, entry_name) or
-                    parents[1].aq_base.has_key(entry_name)):
-                raise AttributeError, entry_name
+            base = parents[-1].aq_base
+            if not (hasattr(base, entry_name) or entry_name in base):
+                raise AttributeError(entry_name)
 
         # After traversal post traversal hooks aren't available anymore
         del self._post_traverse