Index: Lib/urllib.py
===================================================================
--- Lib/urllib.py	(revision 81076)
+++ Lib/urllib.py	(working copy)
@@ -27,6 +27,7 @@
 import os
 import time
 import sys
+import re
 from urlparse import urljoin as basejoin
 
 __all__ = ["urlopen", "URLopener", "FancyURLopener", "urlretrieve",
@@ -1162,8 +1163,11 @@
 def unquote(s):
     """unquote('abc%20def') -> 'abc def'."""
     res = s.split('%')
-    for i in xrange(1, len(res)):
-        item = res[i]
+    if len(res) == 1:
+        return s
+    i = 0
+    for item in res[1:]:
+        i += 1
         try:
             res[i] = _hextochr[item[:2]] + item[2:]
         except KeyError:
@@ -1180,9 +1184,17 @@
 always_safe = ('ABCDEFGHIJKLMNOPQRSTUVWXYZ'
                'abcdefghijklmnopqrstuvwxyz'
                '0123456789' '_.-')
+_unsafe_pattern = r'[^%s%%s]' % re.escape(always_safe)
+_safe_map = dict((c, c) for c in always_safe)
+for i in xrange(0x80):
+    c = chr(i)
+    if c not in _safe_map:
+        _safe_map[c] = '%%%02X' % i
+_safe_map.update((chr(i), '%%%02X' % i) for i in xrange(0x80, 0x100))
 _safemaps = {}
 
-def quote(s, safe = '/'):
+
+def quote(s, safe='/'):
     """quote('abc def') -> 'abc%20def'
 
     Each part of a URL, e.g. the path info, the query, etc., has a
@@ -1203,27 +1215,27 @@
     called on a path where the existing slash characters are used as
     reserved characters.
     """
+    if not s:
+        return s
     cachekey = (safe, always_safe)
     try:
-        safe_map = _safemaps[cachekey]
+        (is_unsafe, safe_get) = _safemaps[cachekey]
     except KeyError:
-        safe += always_safe
-        safe_map = {}
-        for i in range(256):
-            c = chr(i)
-            safe_map[c] = (c in safe) and c or ('%%%02X' % i)
-        _safemaps[cachekey] = safe_map
-    res = map(safe_map.__getitem__, s)
-    return ''.join(res)
+        pattern = _unsafe_pattern % re.escape(safe)
+        safe_map = _safe_map.copy()
+        safe_map.update((c, c) for c in safe)
+        (is_unsafe, safe_get) = _safemaps[cachekey] = \
+            re.compile(pattern).search, safe_map.__getitem__
+    return ''.join(map(safe_get, s)) if is_unsafe(s) else s
 
-def quote_plus(s, safe = ''):
+def quote_plus(s, safe=''):
     """Quote the query fragment of a URL; replacing ' ' with '+'"""
     if ' ' in s:
         s = quote(s, safe + ' ')
         return s.replace(' ', '+')
     return quote(s, safe)
 
-def urlencode(query,doseq=0):
+def urlencode(query, doseq=0):
     """Encode a sequence of two-element tuples or dictionary into a URL query string.
 
     If any values in the query arg are sequences and doseq is true, each