Use string.ascii_letters instead of string.letters (SF bug #226706).
diff --git a/Lib/Cookie.py b/Lib/Cookie.py
index dd116b7..3fc2ffc 100644
--- a/Lib/Cookie.py
+++ b/Lib/Cookie.py
@@ -249,7 +249,7 @@
# _LegalChars is the list of chars which don't require "'s
# _Translator hash-table for fast quoting
#
-_LegalChars = string.letters + string.digits + "!#$%&'*+-.^_`|~"
+_LegalChars = string.ascii_letters + string.digits + "!#$%&'*+-.^_`|~"
_Translator = {
'\000' : '\\000', '\001' : '\\001', '\002' : '\\002',
'\003' : '\\003', '\004' : '\\004', '\005' : '\\005',