traversal bug with OFS.Application.Application

After upgrading to Zope 2.9.2 from 2.9.0 I found that one my applications 
wasn't working anymore.

It depended on being able to bind a page template to 
OFS.Application.Application and through some examination I found a small bug 
in the traversal fallback changes that were made recently.

It basically boils down to OFS.Application.Application's __bobo_traverse__ 
raises NotFound when there is a valid REQUEST.

I've attached a unit test that demonstrates the problem and also the small 
patch which fixes it.

PS. There are two questions I had for more experienced testers on this list:

1. Why does http() return 404 but then actually return the correct content in 
the test case I added?

2. Why must I use zope2.View instead of zope2.Public.  If I use zope2.Public I 
get authentication errors?

-- 
Jordan Baker (jbb@xxxxxxxxxxxxx)

===================================================================
Index: browser/tests/test_traversable.py
===================================================================
--- browser/tests/test_traversable.py   (revision 66357)
+++ browser/tests/test_traversable.py   (working copy)
@@ -258,7 +258,46 @@
       >>> tearDown()
     """

+def test_traverse_ofs_application():
+  """
+  Test for Five fallback when traversing OFS.Application.Application.
+  In Zope 2.9.2 OFS.Application.Application.__bobo_traverse__ raises NotFound 
when it has a REQUEST and so its impossible to use Five traversal with it.

+  Set up:
+
+
+    >>> from zope.app.testing.placelesssetup import setUp, tearDown
+    >>> setUp()
+
+    >>> configure_zcml = '''
+    ... <configure xmlns="http://namespaces.zope.org/zope";
+    ...            xmlns:five="http://namespaces.zope.org/five";
+    ...            xmlns:browser="http://namespaces.zope.org/browser";>
+    ...   <five:traversable class="OFS.Application.Application"/>
+    ...   <browser:page for="*" name="hello.html" 
template="browser/tests/falcon.pt" permission="zope2.View"/>
+    ... </configure>'''
+
+    >>> import Products.Five
+    >>> from Products.Five import zcml
+    >>> zcml.load_config('configure.zcml', Products.Five)
+    >>> zcml.load_string(configure_zcml)
+
+    >>> print http(r'''
+    ... GET /hello.html HTTP/1.1
+    ...
+    ... ''')
+    HTTP/1.1 404 Not Found
+    Content-Length: 35
+    Content-Type: text/html; charset=iso-8859-15
+    <BLANKLINE>
+    <p>The falcon has taken flight</p>
+    <BLANKLINE>
+
+  Clean up:
+
+    >>> tearDown()
+  """
+
 def test_suite():
     from Testing.ZopeTestCase import FunctionalDocTestSuite
     return FunctionalDocTestSuite()
Index: traversable.py
===================================================================
--- traversable.py      (revision 66357)
+++ traversable.py      (working copy)
@@ -61,7 +61,7 @@
         if hasattr(self, '__fallback_traverse__'):
             try:
                 return self.__fallback_traverse__(REQUEST, name)
-            except (AttributeError, KeyError):
+            except (NotFound, AttributeError, KeyError):
                 pass
         else:
             try: