Set default value for readlines.sizehint to None. Change needed for 2.2.1
as well.
diff --git a/Lib/codecs.py b/Lib/codecs.py
index df203c6..293d5b7 100644
--- a/Lib/codecs.py
+++ b/Lib/codecs.py
@@ -252,7 +252,7 @@
         return self.decode(line, self.errors)[0]
 
 
-    def readlines(self, sizehint=0):
+    def readlines(self, sizehint=None):
 
         """ Read all lines available on the input stream
             and return them as list of lines.