diff -r 0aeaea247d7d Lib/cgi.py
--- a/Lib/cgi.py	Wed Apr 02 12:16:55 2014 -0400
+++ b/Lib/cgi.py	Wed Apr 02 21:48:15 2014 +0200
@@ -1045,7 +1045,7 @@
     return s
 
 
-def valid_boundary(s, _vb_pattern=None):
+def valid_boundary(s):
     import re
     if isinstance(s, bytes):
         _vb_pattern = b"^[ -~]{0,200}[!-~]$"