Forward port fix for LP#213311 from 2.10 branch.

doc/CHANGES.txt

@@ -8,6 +8,9 @@ Zope Changes
 
     Bugs Fixed
 
+      - Launchpad #213311:  Handle "unsubscriptable object" errors
+        during publishing traversal.
+
       - Products.Five: Fixed vocabulary lookup broken in 2.11 beta 1.
         ZopeVocabularyRegistry wasn't hooked up on startup.
 

lib/python/ZPublisher/BaseRequest.py

@@ -121,7 +121,10 @@ class DefaultPublishTraverse(object):
                     pass
 
                 # Lastly we try with key access:
-                subobject = object[name]
+                try:
+                    subobject = object[name]
+                except TypeError: # unsubscriptable
+                    raise KeyError(name)
                 
 
         # Ensure that the object has a docstring, or that the parent

lib/python/ZPublisher/tests/testBaseRequest.py

@@ -244,6 +244,15 @@ class TestBaseRequest(unittest.TestCase):
         r._hold(lambda x: None)
         self.assertEqual(r._held, None)
 
+    def test_traverse_unsubscriptable(self):
+        # See https://bugs.launchpad.net/bugs/213311
+        from ZPublisher import NotFound
+        class _Object(object):
+            pass
+        root = _Object()
+        r = self._makeOne(None)
+        self.assertRaises(NotFound, r.traverse, 'not_found')
+
 
 class TestBaseRequestZope3Views(unittest.TestCase):