diff -r 8ea51e9e7031 -r 3da456d0c885 mercurial/config.py
--- a/mercurial/config.py	Mon Nov 22 17:57:11 2010 +0100
+++ b/mercurial/config.py	Mon Nov 22 18:15:58 2010 +0100
@@ -130,7 +130,7 @@
                 name = m.group(1)
                 if sections and section not in sections:
                     continue
-                if self.get(section, name) != None:
+                if self.get(section, name) is not None:
                     del self._data[section][name]
                 continue