Index: urllib2.py
===================================================================
--- urllib2.py	(revision 46491)
+++ urllib2.py	(working copy)
@@ -297,6 +297,10 @@
     def add_handler(self, handler):
         added = False
         for meth in dir(handler):
+            if meth in ["redirect_request", "do_open", "proxy_open"]:
+                # oops, coincidental match
+                continue
+
             i = meth.find("_")
             protocol = meth[:i]
             condition = meth[i+1:]
Index: test/test_urllib2.py
===================================================================
--- test/test_urllib2.py	(revision 46491)
+++ test/test_urllib2.py	(working copy)
@@ -270,6 +270,27 @@
 
 class OpenerDirectorTests(unittest.TestCase):
 
+    def test_badly_named_methods(self):
+        # test work-around for three methods that accidentally follow the
+        # naming conventions for handler methods
+        # (*_open() / *_request() / *_response())
+
+        # These used to call the accidentally-named methods, causing a
+        # TypeError in real code; here, returning self from these mock
+        # methods would either cause no exception, or AttributeError.
+
+        from urllib2 import URLError
+
+        o = OpenerDirector()
+        meth_spec = [
+            [("do_open", "return self"), ("proxy_open", "return self")],
+            [("redirect_request", "return self")],
+            ]
+        handlers = add_ordered_mock_handlers(o, meth_spec)
+        o.add_handler(urllib2.UnknownHandler())
+        for scheme in "do", "proxy", "redirect":
+            self.assertRaises(URLError, o.open, scheme+"://example.com/")
+
     def test_handled(self):
         # handler returning non-None means no more handlers will be called
         o = OpenerDirector()