In walk(), don't die when os.lstat() raises os.error, e.g. because a
file was deleted by a previous call to the visitor function.

This used to be the behavior in 1.5.2 and before, but a patch to avoid
making two stat() calls accidentally broke this in 2.0.

Moshe, this would be a good one for 2.0.1 too!
diff --git a/Lib/posixpath.py b/Lib/posixpath.py
index 223d6ba..6bf40f8 100644
--- a/Lib/posixpath.py
+++ b/Lib/posixpath.py
@@ -269,7 +269,10 @@
     func(arg, top, names)
     for name in names:
         name = join(top, name)
-        st = os.lstat(name)
+        try:
+            st = os.lstat(name)
+        except os.error:
+            continue
         if stat.S_ISDIR(st[stat.ST_MODE]):
             walk(name, func, arg)