combined patches from http://bugs.python.org/issue3187

Lib/genericpath.py

Index: Lib/genericpath.py
===================================================================
--- Lib/genericpath.py	(revision 66736)
+++ Lib/genericpath.py	(working copy)
@@ -87,6 +87,7 @@
 
     Extension is everything from the last dot to the end, ignoring
     leading dots.  Returns "(root, ext)"; ext may be empty."""
+    # NOTE: This code must work for text and bytes strings.
 
     sepIndex = p.rfind(sep)
     if altsep:
@@ -98,8 +99,8 @@
         # skip all leading dots
         filenameIndex = sepIndex + 1
         while filenameIndex < dotIndex:
-            if p[filenameIndex] != extsep:
+            if p[filenameIndex:filenameIndex+1] != extsep:
                 return p[:dotIndex], p[dotIndex:]
             filenameIndex += 1
 
-    return p, ''
+    return p, p[:0]