diff -r 8ea51e9e7031 -r 3da456d0c885 contrib/check-code.py
--- a/contrib/check-code.py	Mon Nov 22 17:57:11 2010 +0100
+++ b/contrib/check-code.py	Mon Nov 22 18:15:58 2010 +0100
@@ -150,6 +150,8 @@
     (r'ui\.(status|progress|write|note|warn)\([\'\"]x',
      "warning: unwrapped ui message"),
     (r' is\s+(not\s+)?["\'0-9-]', "object comparison with literal"),
+    (r' [=!]=\s+(True|False|None)',
+     "comparison with singleton, use 'is' or 'is not' instead"),
 ]
 
 pyfilters = [